如何使用php和mysql在一个表中搜索记录是否存在

Question

I use php and mysql. I have two tables,

table A (Id: auto-increment , idno) table B (Id:auto-increment, sidno) .

Table A contains about 3000 records and Table B contains about 27000 records. I want to search whether each of the records in table A exist in table B, if not print the records that does not exist in table B.

I tried to retrieve the records in table A and checking them against table A, but I could not succeed. And it took a very long time to finished the query.

And I have searched throughout but could not get something like this.

Please can anybody help me.

Thanks!

Answer 1

The following query might return all the idno which are not in table B

 SELECT * FROM tableA WHERE `idno` NOT IN (SELECT `sidno` FROM tableB)

SQL Fiddle Demo

Answer 2

Try this

   SELECT * FROM table2 t where sid NOT IN (select id from table1) ;

Demo

Answer 3

like this

select * from tableA where Minus select id from where tableA.id=tableB.id;

MINUS http://www.techonthenet.com/sql/minus.php

Answer 4

Ok. Try this:

SELECT tableB.Id, tableB.sidno
FROM tableA
RIGHT JOIN tableB ON tableA.Id = tableB.ID
WHERE tableA.Id = 'NULL';

This should give you all the records you want.