Explain basic SQL syntax and SQL syntax

Explain basic SQL syntax and SQL syntax

1. Create a database

Create database Name

2. delete a database

Drop database name

3. Back up SQL server

The device that creates the backup data

Use master

Exec sp_addumpdevice 'name', 'new name', 'path'

Start backup

Backup database pubs to new name

4. Create a table

Create table Name (column name 1, column name 2)

5. Create a new table based on an existing table

Create table new table name like old table name

Create table new table name as select column name from old table name defintion only

6. Add a column

Alter table name add column Name Data Type

7. Add a primary key

Alter table name add primary key (column name)

8. The auto-increment id attribute is added with 1 each time starting from 1.

Identity (1, 1)

9. Create an index

Create index name on table name (column name)

10. delete an index

Drop index idx_name

11. CTE Query

;with t as(select openid,ROW_NUMBER()over(partition by openid order byopenid)as rowfrom #temp)delete t where row>1

12. case when usage (modify the table name id. If the name of t is not blank, it is still the name of t. Otherwise, it is changed to the name of the table, output modified data to a temporary table)

Update pnset pn. id = case when t. id> ''then t. id else pn. id endoutput deleted. id into temporary table from table name pn with (nolock) join # temp t

13. query, insert, delete, sum, average, and maximum

Select * from tableinsert into new_table (id, name) values (1, 'zhang san') delete from table where range select sum (field1) as sumvalue from table1select avg (field1) as avgvalue from table1select max (field1) as maxvalue from table1

I hope this article will help you explain the basic SQL syntax through the above content.

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