Introduction
    
     PDO_SQLSRV is a driver that implements the PHP
     Data Objects (PDO) interface
     to enable access from PHP to MS SQL Server (starting with SQL Server 2005) 
     and SQL Azure databases.
    
    
   
 Installation
 
  The most recent version of the driver is available for download here:
  » SQLSRV download.
  The driver sources are hosted in a » public repository.
 
 
  For more information about system requirements, see 
  » SQLSRV System Requirements.
 
 
  On Windows the PDO_SQLSRV extension is enabled by downloading and adding appropriate DLL files to your PHP
  extension directory and the corresponding entry to the php.ini file.
 
 
  On Linux and macOS, the PDO_SQLSRV extension can be installed using » PECL.
  See the » installation tutorial for details.
 
 
   
 Predefined Constants
 The constants below are defined by
this driver, and will only be available when the extension has been either
compiled into PHP or dynamically loaded at runtime. In addition, these
driver-specific constants should only be used if you are using this driver.
Using driver-specific attributes with another driver may result in
unexpected behaviour. PDO::getAttribute() may be used to
obtain the PDO::ATTR_DRIVER_NAME attribute to check the
driver, if your code can run against multiple drivers.
 
  
   - 
    PDO::SQLSRV_TXN_READ_UNCOMMITTED(int)
- 
    
     This constant is an acceptable value for the SQLSRV DSN key TransactionIsolation. 
     This constant sets the transaction isolation level for the connection to 
     Read Uncommitted.
    
   
- 
    PDO::SQLSRV_TXN_READ_COMMITTED(int)
- 
    
     This constant is an acceptable value for the SQLSRV DSN key TransactionIsolation. 
     This constant sets the transaction isolation level for the connection to 
     Read Committed.
    
   
- 
    PDO::SQLSRV_TXN_REPEATABLE_READ(int)
- 
    
     This constant is an acceptable value for the SQLSRV DSN key TransactionIsolation. 
     This constant sets the transaction isolation level for the connection to 
     Repeateable Read.
    
   
- 
    PDO::SQLSRV_TXN_SNAPSHOT(int)
- 
    
     This constant is an acceptable value for the SQLSRV DSN key TransactionIsolation. 
     This constant sets the transaction isolation level for the connection to Snapshot.
    
   
- 
    PDO::SQLSRV_TXN_SERIALIZABLE(int)
- 
    
     This constant is an acceptable value for the SQLSRV DSN key TransactionIsolation. 
     This constant sets the transaction isolation level for the connection to 
     Serializable.
    
   
- 
    PDO::SQLSRV_ENCODING_BINARY(int)
- 
    
     Specifies that data is sent/retrieved as a raw byte stream to/from the server 
     without performing encoding or translation. This constant can be passed to 
     PDOStatement::setAttribute, PDO::prepare, PDOStatement::bindColumn, and 
     PDOStatement::bindParam.
    
   
- 
    PDO::SQLSRV_ENCODING_SYSTEM(int)
- 
    
     Specifies that data is sent/retrieved to/from the server as 8-bit characters 
     as specified in the code page of the Windows locale that is set on the system. 
     Any multi-byte characters or characters that do not map into this code page 
     are substituted with a single byte question mark (?) character. This constant 
     can be passed to PDOStatement::setAttribute, PDO::setAttribute, PDO::prepare, 
     PDOStatement::bindColumn, and PDOStatement::bindParam.
    
   
- 
    PDO::SQLSRV_ENCODING_UTF8(int)
- 
    
     Specifies that data is sent/retrieved to/from the server in UTF-8 encoding. 
     This is the default encoding. This constant can be passed to 
     PDOStatement::setAttribute, PDO::setAttribute, PDO::prepare, 
     PDOStatement::bindColumn, and PDOStatement::bindParam.
    
   
- 
    PDO::SQLSRV_ENCODING_DEFAULT(int)
- 
    
     Specifies that data is sent/retrieved to/from the server according to 
     PDO::SQLSRV_ENCODING_SYSTEM if specified during connection. The connection's 
     encoding is used if specified in a prepare statement. This constant can be 
     passed to PDOStatement::setAttribute, PDO::setAttribute, PDO::prepare, 
     PDOStatement::bindColumn, and PDOStatement::bindParam.
    
   
- 
    PDO::SQLSRV_ATTR_QUERY_TIMEOUT(int)
- 
    
     A non-negative integer representing the timeout period, in seconds. Zero (0) 
     is the default and means no timeout. This constant can be passed to 
     PDOStatement::setAttribute, PDO::setAttribute, and PDO::prepare.
    
   
- 
    PDO::SQLSRV_ATTR_DIRECT_QUERY(int)
- 
    
     Indicates that a query should be executed directly, without being prepared. 
     This constant can be passed to PDO::setAttribute, and PDO::prepare. For more 
     information, see 
     » Direct and Prepared Statement Execution.