Comments

The methods for commenting on SQL statements and database objects are different.

Comments on SQL statements

For general SQL statements, seekdb supports the following three methods:

• From # to the end of the line, you can comment on a line.

• From -- to the end of the line, you can comment on a line.

• From /* to */, you can comment on multiple lines.

  info

  SQL statements do not support nested comments.

In addition, seekdb supports treating the statements within /*! as SQL statements and executing the comments. If a syntax error occurs within /*!, the database will treat it as a comment by default.

The format of a comment is as follows:

/*![continuous numeric characters representing the version number]<space><any SQL statement>*/

• Example 1: Create a hash partitioned table named t1 with 8 partitions.

  CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 INT) /*!50100
      PARTITION BY HASH(c1) PARTITIONS 8*/;
  Query OK, 0 rows affected (0.098 sec)

• Example 2: Use ENABLE KEYS to update non-unique indexes and DISABLE KEYS to temporarily skip updates during batch inserts. After all indexes are inserted, update the indexes.

  /*!ALTER TABLE t1 DISABLE KEYS */;
  Query OK, 0 rows affected (0.000 sec)
  
  /*!ALTER TABLE t1 ENABLE KEYS */;
  Query OK, 0 rows affected (0.000 sec)

• Example 3: Support the DROP IF EXISTS syntax in PL.

  /*!50003 DROP PROCEDURE IF EXISTS */;
  Query OK, 0 rows affected (0.000 sec)

Comments on database objects

In DDL statements, you can specify comments for database objects using the COMMENT clause. Here is an example:

CREATE TABLE tbl1(pk INT PRIMARY KEY COMMENT 'Primary key');
Query OK, 0 rows affected (0.073 sec)