Help Center/ GaussDB(DWS)/ SQL Syntax Reference/ SQL Syntax Reference (9.1.0.x)/ TCL Syntax/ BEGIN
Updated on 2024-09-02 GMT+08:00
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BEGIN

Function

BEGIN may be used to initiate an anonymous block or a single transaction. This section describes the syntax of BEGIN used to initiate an anonymous block. For details about the BEGIN syntax that initiates transactions, see START TRANSACTION.

An anonymous block is a structure that can dynamically create and execute stored procedure code instead of permanently storing code as a database object in the database.

Precautions

None

Syntax

  • Enable an anonymous block: 
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    [DECLARE [declare_statements]] 
BEGIN
execution_statements  
END;
/
  • -- Start a transaction: 
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    BEGIN [ WORK | TRANSACTION ]
  [ 
    { 
       ISOLATION LEVEL { READ COMMITTED | READ UNCOMMITTED | SERIALIZABLE | REPEATABLE READ }
       | { READ WRITE | READ ONLY }
      } [, ...] 
  ];

Parameter Description

  • declare_statements

    Declares a variable, including its name and type, for example, sales_cnt int.

  • execution_statements

    Specifies the statement to be executed in an anonymous block.

    Value range: an existing function name

Examples

  • Start a transaction block. 
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    BEGIN;
  • Start a transaction block at the REPEATABLE READ isolation level. 
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    BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
  • Generate a string using an anonymous block. 
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    BEGIN
dbms_output.put_line('Hello');
END;
/

Helpful Links

START TRANSACTION

Parent topic: TCL Syntax