将随机数据插入到 MySql 中的表中

Question

Could someone please help me? I don't know what the problem here

DROP PROCEDURE IF EXISTS insertRandom;
CREATE PROCEDURE insertRandom()
BEGIN
DECLARE mytime timestamp;

    SET mytime := '2009-01-01 00:00:00'
BEGIN
 test_loop : LOOP
    while mytime < now()
        mytime = mytime + interval '8 hours';
        insert into tempdata(temp_val, datum) values((select random()*(110)-10), mytime);
  END LOOP; 
END;

CALL insertRandom;

SELECT * FROM `temp_table`;

Answer 1

Looks like a semicolon in the procedure body is terminating the statement. We need MySQL to see the CREATE PROCEDURE as a single statement, but MySQL is chopping the statement off, seeing a complete statement when it sees a semicolon.

The default statement delimiter in MySQL is semicolon ; character. The default delimiter can be overridden; we change with the DELIMITER statement.

Example here of temporarily modifying the statement delimiter to be two dollar sign characters $$ . Within the procedure body, occurrences of the semicolon character won't terminate the statement... MySQL will keep reading until it finds two dollar sign characters. (Goes without saying that the procedure body shouldn't contain $$ )

DELIMITER $$ 

DROP PROCEDURE IF EXISTS insertRandom $$

CREATE PROCEDURE insertRandom()
  ...
  ...
  ...
END$$

DELIMITER ;

CALL insertRandom();

Note that we use the DELIMITER statement to change the delimiter back to the semicolon character. I did not check the body of the procedure for other syntax errors; but some things stick out. For example, this looks wrong

mytime = mytime + interval '8 hours'; 

that should probably be SET statement, and the syntax is like this:

SET mytime = mytime + INTERVAL 8 HOUR;

In the SET statement, we can use the := in place of = as the assignment operator, so equivalent

SET mytime := mytime + INTERVAL 8 HOUR;

For looping withing a MySQL stored program, we can do a LOOP ... END LOOP and include a LEAVE statement, or we can use a WHILE loop, or ...

Syntax documented here:

https://dev.mysql.com/doc/refman/5.7/en/while.html

https://dev.mysql.com/doc/refman/5.7/en/loop.html

Answer 2

You have many errors in your code

Use this Procedure instead

DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `insertRandom`()
BEGIN
DECLARE mytime timestamp;

    SET mytime := '2009-01-01 00:00:00';
DROP TEMPORARY TABLE IF EXISTS tempdata;
CREATE TEMPORARY TABLE tempdata (temp_val BIGINT, datum timestamp);
 test_loop : LOOP
    IF mytime >= now() THEN
        LEAVE  test_loop;
    END  IF;
        SET mytime = TIMESTAMPADD(HOUR,8,mytime);
        insert into tempdata(temp_val, datum) values((select (rand()*110)-10), mytime);
  END LOOP; 
END$$
DELIMITER ;

And then

call insertRandom();
SELECT * FROM tempdata;