Compound build parsing in SQL

Only one primary key per table
Unique keys/constraints can be multiple

A composite primary key refers to a compound unique, such as:
1 1
1 2
2 1
2 2

A single column is not the only one, but the combination is unique.

1  Create TableTable name (field name 1Int  not Null,2Field Name 2nvarchar( -) not Null Primary Key(field name 1, field Name 2),3 field Name 3 ......4 field name N ......) 5 To change the table structure after the table is built:6  7      CREATE TABLETable name (field name 1Int  not Null,8Field Name 2nvarchar( -) not Null9 field Name 3 ......Ten field name N ......) One     GO A   -     ALTER TABLETable name with NOCHECK ADD  -     CONSTRAINT [pk_ Table name] PRIMARY KEY  nonclustered  the      ( -           [Field Name 1], -           [Field Name 2] -      ) +     GO

Compound build parsing in SQL