Insert the data into Table C IF The data is not in Table B while Comparing to Table A in MySQL?
For this, use left join on table A and B. Let us create the first table −
mysql> create table demo20
−> (
−> id int,
−> name varchar(20)
−> );
Query OK, 0 rows affected (1.87 sec)
Insert some records into the table with the help of insert command −
mysql> insert into demo20 values(100,'John');
Query OK, 1 row affected (0.07 sec)
mysql> insert into demo20 values(101,'Bob');
Query OK, 1 row affected (0.24 sec)
mysql> insert into demo20 values(102,'Mike');
Query OK, 1 row affected (0.12 sec)
mysql> insert into demo20 values(103,'Carol');
Query OK, 1 row affected (0.15 sec)
Display records from the table using select statement −
mysql− select *from demo20;
This will produce the following output −
+------+-------+
| id | name |
+------+-------+
| 100 | John |
| 101 | Bob |
| 102 | Mike |
| 103 | Carol |
+------+-------+
4 rows in set (0.00 sec)
Following is the query to create second table −
mysql> create table demo21
−> (
−> id int,
−> name varchar(20)
−> );
Query OK, 0 rows affected (1.70 sec)
Insert some records into the table with the help of insert command −
mysql> insert into demo21 values(100,'Sam');
Query OK, 1 row affected (0.12 sec)
mysql> insert into demo21 values(101,'Adam');
Query OK, 1 row affected (0.14 sec)
mysql> insert into demo21 values(133,'Bob');
Query OK, 1 row affected (0.13 sec)
mysql> insert into demo21 values(145,'David');
Query OK, 1 row affected (0.15 sec)
Display records from the table using select statement −
mysql> select *from demo21;
This will produce the following output −
+------+-------+
| id | name |
+------+-------+
| 100 | Sam |
| 101 | Adam |
| 133 | Bob |
| 145 | David |
+------+-------+
4 rows in set (0.00 sec)
Following is the query to create third table −
mysql> create table demo22
−> (
−> id int,
−> name varchar(20)
−> );
Query OK, 0 rows affected (1.39 sec)
Now, let’s say, demo20 has table name A, demo21 has B and demo22 has C. The query is as follows to insert data into table C if data is not in table B comparing to A −
mysql> insert into demo22(id,name)
−> select tbl1.id,tbl1.name from demo20 tbl1
−> left join demo21 tbl2 on tbl2.id=tbl1.id
−> where tbl2.id is null;
Query OK, 2 rows affected (0.21 sec)
Records: 2 Duplicates: 0 Warnings: 0
Display records from the table using select statement −
mysql> select *from demo22;
This will produce the following output −
+------+-------+
| id | name |
+------+-------+
| 102 | Mike |
| 103 | Carol |
+------+-------+
2 rows in set (0.00 sec)
Published on 19-Nov-2020 16:06:23
