MySQL SELECT from table A that does not exist in table B using JOINS?
To SELECT from table A that does not exist in table B, you can use left join. Following is the syntax −
select yourTableNameA.*
from yourTableNameA left join yourTableNameB on yourTableNameA.yourColumnName =
yourTableNameB.yourColumnName
where yourTableNameB.yourColumnName
IS NULL;
Let us first create a table. Following is the query −
<table_A>
mysql> create table table_A
-> (
-> Value int
-> );
Query OK, 0 rows affected (1.10 sec)
Following is the query to insert records in the table using insert command −
mysql> insert into table_A values(10);
Query OK, 1 row affected (0.32 sec)
mysql> insert into table_A values(15);
Query OK, 1 row affected (0.10 sec)
mysql> insert into table_A values(35);
Query OK, 1 row affected (0.21 sec)
mysql> insert into table_A values(45);
Query OK, 1 row affected (0.13 sec)
Following is the query to display all records from the table using select statement −
mysql> select *from table_A;
This will produce the following output −
+-------+
| Value |
+-------+
| 10 |
| 15 |
| 35 |
| 45 |
+-------+
4 rows in set (0.00 sec)
Let us create another table. Following is the query −
<table_B>
mysql> create table table_B
-> (
-> Value int
-> );
Query OK, 0 rows affected (0.51 sec)
Following is the query to insert some records in the table using insert command −
mysql> insert into table_B values(10);
Query OK, 1 row affected (0.18 sec)
mysql> insert into table_B values(20);
Query OK, 1 row affected (0.12 sec)
mysql> insert into table_B values(35);
Query OK, 1 row affected (0.23 sec)
mysql> insert into table_B values(60);
Query OK, 1 row affected (0.12 sec)
Following is the query to display all records from the table using a select statement −
mysql> select *from table_B;
This will produce the following output −
+-------+
| Value |
+-------+
| 10 |
| 20 |
| 35 |
| 60 |
+-------+
4 rows in set (0.00 sec)
Following is the query to select from table A that does not exist in table B with LEFT JOIN −
mysql> select table_A.*
-> from table_A left join table_B on table_A.Value = table_B.Value
-> where table_B.Value IS NULL;
This will produce the following output −
+-------+
| Value |
+-------+
| 15 |
| 45 |
+-------+
2 rows in set (0.04 sec)
Published on 15-Apr-2019 11:38:30
