SQL Server connection left connection, right connection, full connection

Innerjoin (1st writing methods) selecta. name, B. namefromt_Table1ajoint_Table2bona.IDb.ID (2nd methods) selecta. nameb. namefromt_Table1ainnerjoint_Table2bona.IDb.ID left join (the right join is completely simple, so it will not be written)

Inner join (1st statements) select. name, B. name from t_Table1 a join t_Table2 B on. ID = B. ID (2nd statements) select. name B. name from t_Table1 a inner join t_Table2 B on. ID = B. ID: left join between two tables (the right join is completely simple, so it will not be written)

Inner join

(1st statements) select a. Name, B. Name from t_Table1 a join t_Table2 B on a. ID = B. ID

(2nd statements) select a. Name B. Name from t_Table1 a inner join t_Table2 B on a. ID = B. ID

Left join between the two tables (the right join is completely simple, so it will not be written)

Select a. Name, B. Name from t_table1 a left join t_table B on a. ID = B. ID

4 left join between tables (t_Table1 requires left join t_Table2 and left join t_Table3, t_Table4 is useless)

Select a. Name, B. Name, c. Name

From t_Table1 a left join t_Table2 B on a. ID = B. ID left join t_Table3 c on a. ID = c. ID,

T_table4 d

Where a. ID = d. ID

And other connections

Select a. Name, B. Name from t_Table1 a, t_Table B

Where a. ID = B. ID

Full join)

Select a. Name, B. Name from t_table1 a full join t_Table2 B on a. ID = B. ID