3.7 Utility Statements

3.7.1 USE

USE db_name

例:

use TESTDB;

3.7.2 EXPLAIN

EXPLAIN explainable_stmt

 SELECT statement
| DELETE statement
| INSERT statement
| REPLACE statement
| UPDATE statement

注意事项:

  1. INSERT中表不能为自增序列表
    例:

    explain SELECT select * from a_test where id=1;
    
  2. 在dble中,EXPLAIN 不等价于于DESC

3.7.3 EXPLAIN2

EXPLAIN2 DATANODE=node_name sql=sql_stmt

例:

explain2 datanode=dn2 sql=select * from a_test where id=1;

3.7.4 DESC

{DESCRIBE | DESC} tbl_name [col_name | wild]

例:

DESC a_test id;

注意: 在dble中,EXPLAIN 不等价于于DESC

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