A pure Go MSSQL driver for Go's database/sql package
Install
Requires Go 1.8 or above.
Install with go get github.com/denisenkom/go-mssqldb .
Connection Parameters and DSN
The recommended connection string uses a URL format: sqlserver://username:password@host/instance?param1=value¶m2=value Other supported formats are listed below.
Common parameters:
user id- enter the SQL Server Authentication user id or the Windows Authentication user id in the DOMAIN\User format. On Windows, if user id is empty or missing Single-Sign-On is used. The user domain sensitive to the case which is defined in the connection string.passworddatabaseconnection timeout- in seconds (default is 0 for no timeout), set to 0 for no timeout. Recommended to set to 0 and use context to manage query and connection timeouts.dial timeout- in seconds (default is 15), set to 0 for no timeoutencryptdisable- Data send between client and server is not encrypted.false- Data sent between client and server is not encrypted beyond the login packet. (Default)true- Data sent between client and server is encrypted.
app name- The application name (default is go-mssqldb)
Connection parameters for ODBC and ADO style connection strings:
server- host or host\instance (default localhost)port- used only when there is no instance in server (default 1433)
Less common parameters:
keepAlive- in seconds; 0 to disable (default is 30)failoverpartner- host or host\instance (default is no partner).failoverport- used only when there is no instance in failoverpartner (default 1433)packet size- in bytes; 512 to 32767 (default is 4096)- Encrypted connections have a maximum packet size of 16383 bytes
- Further information on usage: https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/configure-the-network-packet-size-server-configuration-option
log- logging flags (default 0/no logging, 63 for full logging)- 1 log errors
- 2 log messages
- 4 log rows affected
- 8 trace sql statements
- 16 log statement parameters
- 32 log transaction begin/end
TrustServerCertificate- false - Server certificate is checked. Default is false if encypt is specified.
- true - Server certificate is not checked. Default is true if encrypt is not specified. If trust server certificate is true, driver accepts any certificate presented by the server and any host name in that certificate. In this mode, TLS is susceptible to man-in-the-middle attacks. This should be used only for testing.
certificate- The file that contains the public key certificate of the CA that signed the SQL Server certificate. The specified certificate overrides the go platform specific CA certificates.hostNameInCertificate- Specifies the Common Name (CN) in the server certificate. Default value is the server host.ServerSPN- The kerberos SPN (Service Principal Name) for the server. Default is MSSQLSvc/host:port.Workstation ID- The workstation name (default is the host name)ApplicationIntent- Can be given the valueReadOnlyto initiate a read-only connection to an Availability Group listener. Thedatabasemust be specified when connecting withApplication Intentset toReadOnly.
The connection string can be specified in one of three formats:
- URL: with
sqlserverscheme. username and password appears before the host. Any instance appears as the first segment in the path. All other options are query parameters. Examples:
sqlserver://username:password@host/instance?param1=value¶m2=valuesqlserver://username:password@host:port?param1=value¶m2=valuesqlserver://sa@localhost/SQLExpress?database=master&connection+timeout=30// `SQLExpress instance.sqlserver://sa:mypass@localhost?database=master&connection+timeout=30// username=sa, password=mypass.sqlserver://sa:mypass@localhost:1234?database=master&connection+timeout=30// port 1234 on localhost.sqlserver://sa:my%7Bpass@somehost?connection+timeout=30// password is "my{pass"
A string of this format can be constructed using the URL type in the net/url package.
query := url.Values{}
query.Add("app name", "MyAppName")
u := &url.URL{
Scheme: "sqlserver",
User: url.UserPassword(username, password),
Host: fmt.Sprintf("%s:%d", hostname, port),
// Path: instance, // if connecting to an instance instead of a port
RawQuery: query.Encode(),
}
db, err := sql.Open("sqlserver", u.String())
- ADO:
key=valuepairs separated by;. Values may not contain;, leading and trailing whitespace is ignored. Examples:
server=localhost\\SQLExpress;user id=sa;database=master;app name=MyAppNameserver=localhost;user id=sa;database=master;app name=MyAppName
- ODBC: Prefix with
odbc,key=valuepairs separated by;. Allow;by wrapping values in{}. Examples:
odbc:server=localhost\\SQLExpress;user id=sa;database=master;app name=MyAppNameodbc:server=localhost;user id=sa;database=master;app name=MyAppNameodbc:server=localhost;user id=sa;password={foo;bar}// Value marked with{}, password is "foo;bar"odbc:server=localhost;user id=sa;password={foo{bar}// Value marked with{}, password is "foo{bar"odbc:server=localhost;user id=sa;password={foobar }// Value marked with{}, password is "foobar "odbc:server=localhost;user id=sa;password=foo{bar// Literal{, password is "foo{bar"odbc:server=localhost;user id=sa;password=foo}bar// Literal}, password is "foo}bar"odbc:server=localhost;user id=sa;password={foo{bar}// Literal{, password is "foo{bar"odbc:server=localhost;user id=sa;password={foo}}bar}// Escaped} with}}`, password is "foo}bar"
Azure Active Directory authentication - preview
The configuration of functionality might change in the future.
Azure Active Directory (AAD) access tokens are relatively short lived and need to be valid when a new connection is made. Authentication is supported using a callback func that provides a fresh and valid token using a connector:
conn, err := mssql.NewAccessTokenConnector(
"Server=test.database.windows.net;Database=testdb",
tokenProvider)
if err != nil {
// handle errors in DSN
}
db := sql.OpenDB(conn)
Where tokenProvider is a function that returns a fresh access token or an error. None of these statements actually trigger the retrieval of a token, this happens when the first statment is issued and a connection is created.
Executing Stored Procedures
To run a stored procedure, set the query text to the procedure name:
var account = "abc"
_, err := db.ExecContext(ctx, "sp_RunMe",
sql.Named("ID", 123),
sql.Named("Account", sql.Out{Dest: &account}),
)
Reading Output Parameters from a Stored Procedure with Resultset
To read output parameters from a stored procedure with resultset, make sure you read all the rows before reading the output parameters:
sqltextcreate := `
CREATE PROCEDURE spwithoutputandrows
@bitparam BIT OUTPUT
AS BEGIN
SET @bitparam = 1
SELECT 'Row 1'
END
`
var bitout int64
rows, err := db.QueryContext(ctx, "spwithoutputandrows", sql.Named("bitparam", sql.Out{Dest: &bitout}))
var strrow string
for rows.Next() {
err = rows.Scan(&strrow)
}
fmt.Printf("bitparam is %d", bitout)
Caveat for local temporary tables
Due to protocol limitations, temporary tables will only be allocated on the connection as a result of executing a query with zero parameters. The following query will, due to the use of a parameter, execute in its own session, and #mytemp will be de-allocated right away:
conn, err := pool.Conn(ctx)
defer conn.Close()
_, err := conn.ExecContext(ctx, "select @p1 as x into #mytemp", 1)
// at this point #mytemp is already dropped again as the session of the ExecContext is over
To work around this, always explicitly create the local temporary table in a query without any parameters. As a special case, the driver will then be able to execute the query directly on the connection-scoped session. The following example works:
conn, err := pool.Conn(ctx)
// Set us up so that temp table is always cleaned up, since conn.Close()
// merely returns conn to pool, rather than actually closing the connection.
defer func() {
_, _ = conn.ExecContext(ctx, "drop table #mytemp") // always clean up
conn.Close() // merely returns conn to pool
}()
// Since we not pass any parameters below, the query will execute on the scope of
// the connection and succeed in creating the table.
_, err := conn.ExecContext(ctx, "create table #mytemp ( x int )")
// #mytemp is now available even if you pass parameters
_, err := conn.ExecContext(ctx, "insert into #mytemp (x) values (@p1)", 1)
Return Status
To get the procedure return status, pass into the parameters a *mssql.ReturnStatus. For example:
var rs mssql.ReturnStatus
_, err := db.ExecContext(ctx, "theproc", &rs)
log.Printf("status=%d", rs)
or
var rs mssql.ReturnStatus
_, err := db.QueryContext(ctx, "theproc", &rs)
for rows.Next() {
err = rows.Scan(&val)
}
log.Printf("status=%d", rs)
Limitation: ReturnStatus cannot be retrieved using QueryRow.
Parameters
The sqlserver driver uses normal MS SQL Server syntax and expects parameters in the sql query to be in the form of either @Name or @p1 to @pN (ordinal position).
db.QueryContext(ctx, `select * from t where ID = @ID and Name = @p2;`, sql.Named("ID", 6), "Bob")
Parameter Types
To pass specific types to the query parameters, say varchar or date types, you must convert the types to the type before passing in. The following types are supported:
- string -> nvarchar
- mssql.VarChar -> varchar
- time.Time -> datetimeoffset or datetime (TDS version dependent)
- mssql.DateTime1 -> datetime
- mssql.DateTimeOffset -> datetimeoffset
- "github.com/golang-sql/civil".Date -> date
- "github.com/golang-sql/civil".DateTime -> datetime2
- "github.com/golang-sql/civil".Time -> time
- mssql.TVP -> Table Value Parameter (TDS version dependent)
Important Notes
- LastInsertId should not be used with this driver (or SQL Server) due to how the TDS protocol works. Please use the OUTPUT Clause or add a
select ID = convert(bigint, SCOPE_IDENTITY());to the end of your query (ref SCOPE_IDENTITY). This will ensure you are getting the correct ID and will prevent a network round trip. - NewConnector may be used with OpenDB.
- Connector.SessionInitSQL may be set to set any driver specific session settings after the session has been reset. If empty the session will still be reset but use the database defaults in Go1.10+.
Features
- Can be used with SQL Server 2005 or newer
- Can be used with Microsoft Azure SQL Database
- Can be used on all go supported platforms (e.g. Linux, Mac OS X and Windows)
- Supports new date/time types: date, time, datetime2, datetimeoffset
- Supports string parameters longer than 8000 characters
- Supports encryption using SSL/TLS
- Supports SQL Server and Windows Authentication
- Supports Single-Sign-On on Windows
- Supports connections to AlwaysOn Availability Group listeners, including re-direction to read-only replicas.
- Supports query notifications
Tests
go test is used for testing. A running instance of MSSQL server is required. Environment variables are used to pass login information.
Example:
env SQLSERVER_DSN=sqlserver://user:pass@hostname/instance?database=test1 go test
Deprecated
These features still exist in the driver, but they are are deprecated.
Query Parameter Token Replace (driver "mssql")
If you use the driver name "mssql" (rather then "sqlserver") the SQL text will be loosly parsed and an attempt to extract identifiers using one of
- ?
- ?nnn
- :nnn
- $nnn
will be used. This is not recommended with SQL Server. There is at least one existing won't fix issue with the query parsing.
Use the native "@Name" parameters instead with the "sqlserver" driver name.
Known Issues
- SQL Server 2008 and 2008 R2 engine cannot handle login records when SSL encryption is not disabled. To fix SQL Server 2008 R2 issue, install SQL Server 2008 R2 Service Pack 2. To fix SQL Server 2008 issue, install Microsoft SQL Server 2008 Service Pack 3 and Cumulative update package 3 for SQL Server 2008 SP3. More information: http://support.microsoft.com/kb/2653857
