SQL database-<2> database basic operations

Learn

the basic data types of a database simply before learning the base operation statement:

Data type:
Binary data: stored in 16 binary form
Fixed length: Binary
Variable length: varbinary
Character data:
Char: fixed length
VARCHAR: Not at the same length, but any item length cannot exceed 8KB
Date Time Data:
Datatime (1753-1-1,9999-12-31) smalldatetime (1900-1-1,2079-6-6)

numeric data
Integer data: bigint int samllint tinyint
Real data: Decimal:decimal[p (, s)] where p is the total number of digits, that is, the precision, S is the number of decimal places.
Float
Currency data:
Money
Special data types:
Bit:true, false; Yes, No

Text and image data types:
Texts: Text
Images: Image

Simple Writing specification

The SQL language is case-insensitive and the data in the database is case-sensitive

Encountered keywords can be expanded with [] parentheses

Comments:

--: Single line comment

/* * *: Multi-line Comment

More detailed information can be consulted

First, database operations: Create, delete, modify, rename and other basic operations

Create database name--Build

Drop database name--delete

ALTER DATABASE name--change

Second, data table operation: increase, delete, change, check

SQL database-<2> database basic operations