Question

I wanna insert a row when the name not exists in the table.

When the table is empty,it cannot insert anything, anyone can help me?

Here is my code:

INSERT INTO `ediftpdb`.`users`(
      name
      ,passwd
      ,vendor
    )
    SELECT
      'L001'
      ,'12345678a'
      ,'MKTPLS'
    FROM `ediftpdb`.`users`
    WHERE NOT EXISTS (SELECT * FROM `ediftpdb`.`users` WHERE name='L001' AND vendor = 'MKTPLS' ) LIMIT 1;

P.S.
I found a funny stuff, when ediftpdb.users is empty, code like below returns nothing.

SELECT
  'L001'
  ,'12345678a'
  ,'MKTPLS'
FROM `ediftpdb`.`users`

Answer 1

The better way to do this is to create a unique multi-part index on name and vendor columns:

CREATE UNIQUE INDEX name_vendor ON ediftpdb.users( name, vendor )

Then:

INSERT IGNORE INTO ediftpdb.users ( name, passwd, vendor )
  VALUES ( 'L001', '12345678a', 'MKTPLS' )

will do exactly what you want to do.