SQL table connection view triggers transaction stored procedures

Trancate Delete Common table expression Modify view

Table Union : The number of Union columns has not changed, and the result set can be merged without altering the result structure. Multiple Select. The number of rows increased.

Table Connection

To change the number of columns, a table of 3 columns and 9 columns merged into 12 columns is called a connection

cross-linking : The Cartesian product of crosses two tables. Generate auxiliary table, with old data optimization, need 1234 pure digital continuous according to table

creat table Num15

(

Num INT

)

INSERT INTO NUM15

Internal connection:

External connection:

SQL table connection view triggers transaction stored procedures