SQL-如果没有数据，则插入表中

Question

I'm using MYSQL script and I want to insert some values in a table.

INSERT INTO `testType` (`name`) VALUES ('URL');
INSERT INTO `testType` (`name`) VALUES ('xD');
INSERT INTO `testType` (`name`) VALUES ('LOL');

But I only want to insert if the table is empty in the first place.

I'm not a SQL guy but basically

if(testType.length() == 0 {

    INSERT INTO `testType` (`name`) VALUES ('URL');
    INSERT INTO `testType` (`name`) VALUES ('xD');
    INSERT INTO `testType` (`name`) VALUES ('LOL');

}

How can I do this the simplest and smallest way possible? Thank you.

EDIT: my question is different. I want to insert ALL THE DATA if the table is empty. not only one insert at the time

Answer 1

First, I would suggest doing this in one step:

INSERT INTO testType(name)
    VALUES ('URL'), ('xD'), ('LOL');

Then, you can express this without IF :

INSERT INTO testType(name)
    SELECT t.name
    FROM (SELECT 'URL' as name UNION ALL
          SELECT 'xD' as name UNION ALL
          SELECT 'LOL' as name
         ) t
    WHERE NOT EXISTS (SELECT 1 FROM testType);

Finally, if you want to insert these values if each doesn't exist, then you can let the database do the work. First, define a unique constraint/index on the name (if name is not already the primary key), and then use ON DUPLICATE KEY UPDATE :

CREATE UNIQUE INDEX unq_testtable_name ON testtable(name);

INSERT INTO testType(name)
    VALUES ('URL'), ('xD'), ('LOL')
    ON DUPLICATE KEY UPDATE name = VALUES(name);

Answer 2

Try this:

DECLARE @ExistCount INT;
SET @ExistCount = (SELECT COUNT(1) FROM `testType`);

IF @ExistCount<1
THEN
    INSERT INTO `testType` (`name`) VALUES ('URL'),('xD'),('LOL');
END IF;

Answer 3

You can use stored procedure

DELIMITER //

CREATE PROCEDURE `proc1` ()
BEGIN

        SELECT COUNT(*) INTO variable1 FROM testType;
        IF variable1 = 0 THEN
            INSERT INTO `testType` (`name`) VALUES ('URL');
            INSERT INTO `testType` (`name`) VALUES ('xD');
            INSERT INTO `testType` (`name`) VALUES ('LOL');
    END WHILE;
END //