SQL INNER JOIN several uses

Source: Internet
Author: User

INNER JOIN ... The syntax format of on can be summarized as:
From ((Table 1 INNER join table 2 on table 1. Field number = Table 2. Field number) INNER join table 3 on table 1. Field number = Table 3. Field number) INNER join table 4 on member. Field number = Table 4. Field no. = INNER Join Table x on member. Field number = table X. Field number

eg.
Use to connect two data tables:
From the INNER JOIN membersort on Member.membersort=membersort.membersort
The syntax format can be summed up as:
From table 1 INNER JOIN table 2 on table 1. Field number = Table 2. Field number

Use to connect three data tables:
From (Member INNER join Membersort on Member.membersort=membersort.membersort) INNER JOIN memberlevel on Member.memberlev El=memberlevel.memberlevel
The syntax format can be summed up as:
From (table 1 INNER join table 2 on table 1. Field number = Table 2. Field number) INNER JOIN table 3 on table 1. Field number = Table 3. Field number

INNER JOIN Syntax:

INNER join joins two datasheet usage:
SELECT * FROM table 1 INNER JOIN table 2 on table 1. Field number = Table 2. Field number

INNER join joins three datasheet usage:
SELECT * FROM (table 1 INNER join table 2 on table 1. Field number = Table 2. Field number) INNER JOIN table 3 on table 1. Field number = Table 3. Field number

INNER join joins four datasheet usage:
SELECT * FROM (table 1 INNER JOIN table 2 on table 1. Field number = Table 2. Field number) INNER join table 3 on table 1. Field number = Table 3. Field number) INNER join table 4 on member. Field number = Table 4.

INNER join joins five datasheet usage:
SELECT * FROM ((table 1 INNER JOIN table 2 on table 1. Field number = Table 2. Field number) INNER join table 3 on table 1. Field number = Table 3. Field number) INNER join table 4 on member. Field number = Table 4. Field No. NER JOIN table 5 on member. Field number = Table 5. Field number


INNER JOIN (equivalent join) returns only rows with the same join field in two tables
Left JOIN, which returns records that include all records in the left table and the join fields in the right table
Right join returns records that include all the records in the right table and the join fields in the left table

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