API - Connection |

  Tedious ([original](http://tediousjs.github.io/tedious/api-connection.html)) ([raw](?raw))

A Connection instance represents a single connection to a database server.

Only one request at a time may be executed on a connection. Once a Request has been initiated (with callProcedure,execSql, orexecSqlBatch), another should not be initiated until the Request's completion callback is called.

new Connection(config)

var Connection = require('tedious').Connection;
var config = {
  "authentication": {
    ...,
    "options": {...}
  },

  "options": {
    ...
  }
};
var connection = new Connection(config);

// Setup event handler when the connection is established. 
connection.on('connect', function(err) {
  if(err) {
    console.log('Error: ', err)
  }
  // If no error, then good to go...
  executeStatement();
});

// Initialize the connection.
connection.connect();

config

Note: be aware of the different options field:

  1. config.authentication.options

  2. config.options

server

Hostname to connect to.

authentication.type

Type of the authentication method, valid types are default, ntlm,azure-active-directory-default, azure-active-directory-password, azure-active-directory-access-token, azure-active-directory-msi-vm, azure-active-directory-msi-app-service, or azure-active-directory-service-principal-secret

This uses DefaultAzureCredential to try multiple methods of authentication. You can find more information on what values to provide and how to provide them from this Microsoft document. 

"authentication": {
  "type":'azure-active-directory-default',
  ...,
  "options": {
    "clientId": value (Optional)
  }
}           
"authentication": {
  "type":'azure-active-directory-password',
  ...,
  "options": {
    "userName": value,
    "password": value,
    "clientId": value,
    "tenantId": value (Optional)
  }
}           
"authentication": {
  "type":'azure-active-directory-access-token',
  ...,
  "options": {
    "token": value
  }
}

Best Practices

Tedious supports an authentication type: azure-active-directory-password. This is the recommended method because Tedious will handle the process of retrieving the Azure token internally instead of requiring the user to manually retrieve the token as shown below.

How to get the token

There are different approaches if a user actually needs to retrieve a token manually. The details can be found in Microsoft documentation. Here are some examples: * Retrieving the token within an msi-app-service using a PowerShell script: here. * Retrieving the token within an msi-vm using a PowerShell script: here. * Retrieving the token within a JavaScript script: here.

"authentication": {
  "type":'azure-active-directory-msi-vm',
  ...,
  "options": {
    "clientId": value,
    "msiEndpoint": value
  }
    
}           
"authentication": {
  "type":'azure-active-directory-msi-app-service',
  ...,
  "options": {
    "clientId": value,
    "msiEndpoint": value,
    "msiSecret": value
  }
}           
"authentication": {
  "type":'azure-active-directory-service-principal-secret',
  ...,
  "options": {
    "clientId": value,
    "clientSecret": value,
    "tenantId": (Optional)
  }
}

If using NTLM with node 17 or newer, the --openssl-legacy-provider command line flag must be enabled, else an error will be thrown. Check the FAQ for more information.

authentication.options.userName

User name to use for authentication.

authentication.options.password

Password to use for authentication.

authentication.options.domain

Once you set domain for ntlm authentication type, driver will connect to SQL Server using domain login.

authentication.options.token

When using azure-active-directory-access-token authentication type, this is the access token to use for authentication.

authentication.options.clientId

When using azure-active-directory-msi-app-service (optional), azure-active-directory-msi-vm (optional), or azure-active-directory-service-principal-secret authentication type, this is the Application (client) ID of the identity to use for authentication.

authentication.options.clientSecret

When using azure-active-directory-service-principal-secret authentication type, this is a secret associated with the clientId to use for authentication.

options.abortTransactionOnError

A boolean determining whether to rollback a transaction automatically if any error is encountered during the given transaction's execution. This sets the value for SET XACT_ABORT during the initial SQL phase of a connection (documentation).

options.appName

Application name used for identifying a specific application in profiling, logging or tracing tools of SQL Server. (default: Tedious)

options.camelCaseColumns

A boolean, controlling whether the column names returned will have the first letter converted to lower case (true) or not. This value is ignored if you provide a columnNameReplacer. (default: false).

options.cancelTimeout

The number of milliseconds before the cancel (abort) of a request is considered failed (default: 5000).

options.columnNameReplacer

A function with parameters (columnName, index, columnMetaData) and returning a string. If provided, this will be called once per column per result-set. The returned value will be used instead of the SQL-provided column name on row and meta data objects. This allows you to dynamically convert between naming conventions. (default: null).

options.connectionRetryInterval

Number of milliseconds before retrying to establish connection, in case of transient failure. (default:500)

options.connectTimeout

The number of milliseconds before the attempt to connect is considered failed (default: 15000).

options.connectionIsolationLevel

The default isolation level for new connections. All out-of-transaction queries are executed with this setting. The isolation levels are available from require('tedious').ISOLATION_LEVEL .

options.cryptoCredentialsDetails

When options.encrypt is set to true, an object may be supplied that will be used as the secureContext field when callingnew tls.TLSSocket. The available options are listed under tls.createSecureContext. (default: {}).

options.database

Database to connect to (default: dependent on server configuration).

options.datefirst

Sets the first day of the week to a number from 1 through 7.

options.dateFormat

A string representing position of month, day and year in temporal datatypes. (default: mdy)

options.debug.packet

A boolean, controlling whether debug events will be emitted with text describing packet details (default: false).

options.debug.data

A boolean, controlling whether debug events will be emitted with text describing packet data details (default: false).

options.debug.payload

A boolean, controlling whether debug events will be emitted with text describing packet payload details (default: false).

options.debug.token

A boolean, controlling whether debug events will be emitted with text describing token stream tokens (default: false).

options.enableAnsiNull

A boolean, controls the way null values should be used during comparison operation. (default: true)

options.enableAnsiNullDefault

If true, SET ANSI_NULL_DFLT_ON ON will be set in the initial sql. This means new columns will be nullable by default. See the T-SQL documentation for more details. (Default: true).

options.enableAnsiPadding

A boolean, controls if padding should be applied for values shorter than the size of defined column. (default:true)

options.enableAnsiWarnings

If true, SQL Server will follow ISO standard behavior during various error conditions. For details, see documentation. (default: true)

options.enableArithAbort

Ends a query when an overflow or divide-by-zero error occurs during query execution. See documentation for more details. (default: true)

options.enableConcatNullYieldsNull

A boolean, determines if concatenation with NULL should result in NULL or empty string value, more details in documentation. (default: true)

options.enableCursorCloseOnCommit

A boolean, controls whether cursor should be closed, if the transaction opening it gets committed or rolled back. (default: null)

options.enableImplicitTransactions

A boolean, sets the connection to either implicit or autocommit transaction mode. (default: false)

options.enableNumericRoundabort

If false, error is not generated during loss of precession. (default: false)

options.enableQuotedIdentifier

If true, characters enclosed in single quotes are treated as literals and those enclosed double quotes are treated as identifiers. (default: true)

options.encrypt

A string value set to strict enables the TDS 8.0 protocol. Otherwise, encrypt can be set to a boolean value which determines whether or not the connection will be encrypted under the TDS 7.x protocol. (default: true)

options.fallbackToDefaultDb

By default, if the database requested by options.database cannot be accessed, the connection will fail with an error. However, if options.fallbackToDefaultDb is set to true, then the user's default database will be used instead (Default: false).

options.instanceName

The instance name to connect to. The SQL Server Browser service must be running on the database server, and UDP port 1434 on the database server must be reachable.
(no default)
Mutually exclusive with options.port.

options.isolationLevel

The default isolation level that transactions will be run with. The isolation levels are available from require('tedious').ISOLATION_LEVEL .

options.language

Specifies the language environment for the session. The session language determines the datetime formats and system messages. (default: us_english).

options.localAddress

A string indicating which network interface (ip address) to use when connecting to SQL Server.

options.maxRetriesOnTransientErrors

The maximum number of connection retries for transient errors. (default: 3).

options.multiSubnetFailover

Sets the MultiSubnetFailover = True parameter, which can help minimize the client recovery latency when failovers occur. (default: false).

options.packetSize

The size of TDS packets (subject to negotiation with the server). Should be a power of 2. (default: 4096).

options.port

Port to connect to (default: 1433).
Mutually exclusive with options.instanceName.

options.readOnlyIntent

A boolean, determining whether the connection will request read only access from a SQL Server Availability Group. For more information, see here. (default: false).

options.requestTimeout

The number of milliseconds before a request is considered failed, or 0 for no timeout (default: 15000).

options.rowCollectionOnDone

A boolean, that when true will expose received rows in Requests' done* events. See done,doneInProc and doneProc. (default: false)

Caution: If many row are received, enabling this option could result in excessive memory usage.

options.rowCollectionOnRequestCompletion

A boolean, that when true will expose received rows in Requests' completion callback. See new Request. (default: false)

Caution: If many row are received, enabling this option could result in excessive memory usage.

options.tdsVersion

The version of TDS to use. If server doesn't support specified version, negotiated version is used instead. The versions are available from require('tedious').TDS_VERSION.

options.textsize

Specifies the size of varchar(max), nvarchar(max), varbinary(max), text, ntext, and image data returned by a SELECT statement. (default: 2147483647) (Textsize is set by a numeric value.)

options.trustServerCertificate

If "true", the SQL Server SSL certificate is automatically trusted when the communication layer is encrypted using SSL. If "false", the SQL Server validates the server SSL certificate. If the server certificate validation fails, the driver raises an error and terminates the connection. Make sure the value passed to serverName exactly matches the Common Name (CN) or DNS name in the Subject Alternate Name in the server certificate for an SSL connection to succeed. (default: true).

options.useColumnNames

A boolean determining whether to return rows as arrays or key-value collections. (default: false).

options.useUTC

A boolean determining whether to pass time values in UTC or local time. (default: true).

Event: 'connect'

function (err) { }

The attempt to connect and validate has completed.

err

If successfully connected, will be falsey.

If there was a problem (with either connecting or validation), will be an error object.

Event: 'end'

function () { }

The connection has ended. This may be as a result of the client calling close(), the server closing the connection, or a network error.

Event: 'error'

function (err) { }

Internal error occurs.

Event: 'debug'

function (messageText) { }

A debug message is available. It may be logged or ignored.

messageText

The debug message.

Event: 'infoMessage'

function (info) { }

The server has issued an information message.

info

An object with these properties:

number

Error number

state

The error state, used as a modifier to the error number.

class

The class (severity) of the error. A class of less than 10 indicates an informational message.

message

The message text.

procName

The stored procedure name (if a stored procedure generated the message).

lineNumber

The line number in the SQL batch or stored procedure that caused the error. Line numbers begin at 1; therefore, if the line number is not applicable to the message, the value of LineNumber will be 0.

Event: 'errorMessage'

function (error) { }

The server has issued an error message.

error

An object with the same properties as.listed for theinfoMessage event.

Event: 'databaseChange'

function (databaseName) { }

The server has reported that the active database has changed. This may be as a result of a successful login, or a use statement.

databaseName

The name of the new active database

Event: 'languageChange'

function (languageName) { }

The server has reported that the language has changed.

languageName

The newly active language.

Event: 'charsetChange'

function (charset) { }

The server has reported that the charset has changed.

Event: 'secure'

function (cleartext) { }

A secure connection has been established.

connection.connect(callback)

Initialize a connection.

callback

function (err) { }

The callback is called when the connection is either successfully created (on a connect event) or has an error (on a error event). If an error occurs, then err will describe the error.

This parameter is optional, if a user choose to not include this parameter, then they have to call the connection.on('connect', (err) => {}); to check the connection status.

err

If an error occurs, either a connection error or an aggregate error object will be returned.

console.log('Error: ', err)  
err.errors.map(error=>console.log('Error: ', err))

connection.beginTransaction(callback, [name], [isolationLevel])

Start a transaction.

callback

function (err) { }

The callback is called when the request to start the transaction has completed, either successfully or with an error. If an error occurred then err will describe the error.

As only one request at a time may be executed on a connection, another request should not be initiated until this callback is called.

err

If an error occurred, a string with details of the error.

name

A string representing a name to associate with the transaction.

Optional, and defaults to an empty string. Required when isolationLevel is present.

isolationLevel

The isolation level that the transaction is to be run with. The isolation levels are available from require('tedious').ISOLATION_LEVEL .

Optional, and defaults to the Connection's isolation level.

connection.callProcedure(request)

Call a stored procedure represented by request.

request

A Request object representing the request.

connection.cancel()

Cancel currently executed request.

connection.close()

Closes the connection to the database.

The end will be emitted once the connection has been closed.

connection.execSql(request)

Execute the SQL represented by request.

As sp_executesql is used to execute the SQL, if the same SQL is executed multiples times using this function, the SQL Server query optimizer is likely to reuse the execution plan it generates for the first execution. This may also result in SQL server treating the request like a stored procedure which can result in the doneInProc ordoneProc events being emitted instead of thedone event you might expect. UsingexecSqlBatch will prevent this from occurring but may have a negative performance impact.

Beware of the way that scoping rules apply, and how they mayaffect local temp tables. If you're running in to scoping issues, then execSqlBatch may be a better choice. See also issue #24.

request

A Request object representing the request.

connection.commitTransaction(callback)

Commit a transaction.

There should be an active transaction. That is, beginTransaction should have been previously called.

callback

function (err) { }

The callback is called when the request to commit the transaction has completed, either successfully or with an error. If an error occurred then err will describe the error.

As only one request at a time may be executed on a connection, another request should not be initiated until this callback is called.

err

If an error occurred, a string with details of the error.

connection.execSqlBatch(request)

Execute the SQL batch represented by request. There is no param support, and unlike execSql, it is not likely that SQL Server will reuse the execution plan it generates for the SQL.

In almost all cases, execSql will be a better choice.

request

A Request object representing the request.

connection.execBulkLoad(bulkLoad, rows)

Executes a BulkLoad.

rows

The row data. Accepts objects that implements the Iterable or AsyncIterable interface (e.g. a Readable stream or an AsyncGenerator). Each row can either be an array or object. 

const rows = [{col1name: col1data, col2name: col2data, col3name: col3data, ... },  
              [col1data, col2data, col3data, ...],  
              {col2name: col2data}]  
const rows = Readable.from([{col1name: col1data, col2name: col2data, col3name: col3data, ... },  
              [col1data, col2data, col3data, ...],  
              {col2name: col2data}])

connection.execute(request, parameters)

Execute previously prepared SQL, using the supplied parameters.

request

A previously prepared Request.

parameters

An object whose names correspond to the names of parameters that were added to therequest before it was prepared. The object's values are passed as the parameters' values when the request is executed.

connection.prepare(request)

Prepare the SQL represented by the request. The request can then be used in subsequent calls toexecute and unprepare

request

A Request object representing the request.

Parameters only require a name and type. Parameter values are ignored.

connection.reset(callback)

Reset the connection to its initial state. Can be useful for connection pool implementations.

callback

function (err) { }

The callback is called when the connection reset has completed, either successfully or with an error. If an error occurred then err will describe the error.

As only one request at a time may be executed on a connection, another request should not be initiated until this callback is called.

err

If an error occurred, a string with details of the error.

connection.rollbackTransaction(callback)

Rollback a transaction.

There should be an active transaction. That is, beginTransaction should have been previously called.

callback

function (err) { }

The callback is called when the request to rollback the transaction has completed, either successfully or with an error. If an error occurred then err will describe the error.

As only one request at a time may be executed on a connection, another request should not be initiated until this callback is called.

err

If an error occurred, a string with details of the error.

connection.saveTransaction(callback)

Set a savepoint within a transaction.

There should be an active transaction. That is, beginTransaction should have been previously called.

callback

function (err) { }

The callback is called when the request to set a savepoint within the transaction has completed, either successfully or with an error. If an error occurred then err will describe the error.

As only one request at a time may be executed on a connection, another request should not be initiated until this callback is called.

err

If an error occurred, a string with details of the error.

connection.transaction(callback, name, isolationLevel)

Run the given callback after starting a transaction, and commit or rollback the transaction afterwards.

This is a helper that employs beginTransaction,commitTransaction,rollbackTransaction andsaveTransaction to greatly simplify the use of database transactions and automatically handle transaction nesting.

callback

function (err, done) { }

The callback is called when the request to start a transaction (or create a savepoint, in the case of a nested transaction) has completed, either successfully or with an error. If an error occurred, then err will describe the error. If no error occurred, the callback should perform its work and eventually calldone with an error or null (to trigger a transaction rollback or a transaction commit) and an additional completion callback that will be called when the request to rollback or commit the current transaction has completed, either successfully or with an error. Additional arguments given to done will be passed through to this callback.

As only one request at a time may be executed on a connection, another request should not be initiated until the completion callback is called.

err

Pass null to commit the transaction or not null (an error) when the transaction is to be rolled back.

done

This is another callback you provide that tedious calls when it has committed the transaction or a rollback transaction. It will call done with one or more parameters, namely:

err

an indication of any problems with the final commit request

done

Yet another call back with error as first parameter, followed by variable number of arguments as array.

other

the additional parameters you provided to tedious, which tedious will reflect back to you

name

A string representing a name to associate with the transaction.

Optional, and defaults to an empty string. In case of a nested transaction, naming the transaction name has no effect.

isolationLevel

The isolation level that the transaction is to be run with. The isolation levels are available from require('tedious').ISOLATON_LEVEL .

Optional, and defaults to the Connection's isolation level.

Here's the actual parameter input of transaction in TypeScript notation:

transaction <T extends (...args: any[]) => void>(cb: (err: Error | null | undefined, txDone?: (err: Error | null | undefined, done: T, ...args: Parameters<T>) => void) => void, isolationLevel?: typeof ISOLATION_LEVEL[keyof typeof ISOLATION_LEVEL])

connection.unprepare(request)

Release the SQL Server resources associated with a previously prepared request.

request

The request to be unprepared.

connection.newBulkLoad(tableName, options, callback)

Creates a new BulkLoad instance.

tableName

The name of the table to bulk-insert into.

options(optional)

checkConstraints

Honors constraints during bulk load, using T-SQL CHECK_CONSTRAINTS. (default: false)

fireTriggers

Honors insert triggers during bulk load, using the T-SQL FIRE_TRIGGERS. (default: false)

keepNulls

Honors null value passed, ignores the default values set on table, using T-SQL KEEP_NULLS. (default: false)

tableLock

Places a bulk update(BU) lock on table while performing bulk load, using T-SQL TABLOCK. (default: false)

callback

function (err, rowCount) { }

A function which will be called after the BulkLoad finishes executing. rowCount will equal the number of rows inserted.