CodePudding user response:

The two statements that links with the union together

CodePudding user response:

Statements 1

Union all

Statements 2

If it is going to heavy, can put the union all into a union

CodePudding user response:

Added two queries under the field type should agree to write a null as empty
. Select a t1, a t1. B, NOW (), "a" from table1 t1
The union
The select t2. A, t2. B, NOW (), "c" from table1 t2