SQL-另一个表中不存在SELECT行

Question

I'm trying to select the rows not present in table B , based on table A .

Unlike table B , table A has "_00" at the end of the titleid, and the column is called title instead of titleid .

Table A :

id | titleid
---+----------
1  | TEST1_00
2  | TEST2_00
3  | TEST3_00
4  | TEST4_00

Table B :

id | title
---+-------
1  | TEST1
2  | TEST2

I currently have:

SELECT `t1.titleid`
FROM `tableb t1`
LEFT JOIN `tablea t2` ON `t2.title + '_00' = t1.titleid`
WHERE `t2.title` IS NULL

How can I select the values which are present in A but not in B ?

---

Desired output

id | title
---+----------
3  | TEST3_00
4  | TEST4_00

Answer 1

 SELECT t1.titleid
 FROM tablea t1
 LEFT JOIN tableb t2 ON t2.title + '_00' = t1.titleid
 WHERE t2.title IS NULL

You want to pull Data from Table A , do a left join on Table B and pull data where TableB.Title is null .

Your Query was trying to pull data where TableA.Title is NULL .

Answer 2

You need to LEFT JOIN tableb instead if tablea

SELECT `t1.titleid`
FROM `tablea t1`
LEFT JOIN `tableb t2` ON `t1.titleid = t2.title+ '_00'`
WHERE `t2.title` IS NULL

This will show which records in tablea don't have a match in tableb and are null

Answer 3

It is possible to do this like that

SELECT `t1.titleid`
FROM `tablea t1`

WHERE 
NOT EXISTS (SELECT t2.title FROM `tableb t2` WHERE `t1.titleid = t2.title+ '_00'`)

Answer 4

select * from A where SUBSTRING(A.title,0, 6) in (select B.title from B )