SQL Getting Started Classic (fifth edition) Ryan Stephens study notes Part IV: Building Complex database queries

14th: Using subqueries to define indeterminate data

1, sub-query and select in combination with

Select Colum from table where column, where columnb= (select Colum_name from ...);

2, sub-query and inset combined use

Insert table1 Select Column1 from table2 where cloumn2> (select ...);

Insert a few items in table two that meet the criteria into table 1, note: number of items inserted = number of Table1

3, sub-query and update use together

4, sub-query and delete in combination with

15th Chapter: Combining Multiple queries

1. Union

Select ID from Stu Union ID from Jobe; When the ID in the two table is the same, the output is not repeated.

2. UNION ALL

Select ID from STU UNION all ID from Jobe; When the ID in the two table is the same, the output repeats.

SQL Getting Started Classic (fifth edition) Ryan Stephens study notes Part IV: Building Complex database queries