MySQL First lesson

Build Library:

CREATE DATABASE Database name DEFAULT charset= ' UTF8 ';

Create database j18 defaultcharset= ' utf-8 ';

Create Database j18 The default character encoding Utf-8

Drop Database database name; Delete the specified database

Use commands to enter a specified warehouse

Use warehouse name

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because we don't know which libraries are in the system, we use the show databases command line to show those libraries;

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use commands to see which tables are in the library

Show tables;

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To view information for a specified table using SQL statements

Structured Query statements

Select * from table name ; See all the information in the table

data type:

integer: TINYINT 1 bytes -128~127, SMALLINT 2 bytes -32768~32767 INT 4 bytes +- billion,BIGINT 8 bytes decimal: FLOAT ,DOUBLE ,decimal (m,n) the number of digits after the decimal point (M,n) m represents the number of digits in this number,n means that there are several after the decimal point (5,2) 123.22 (5,2) 4.1111 string: CHAR (m)--m represents the length of the string that the field can represent, up to 255 VARCHAR (m)--m indicates the length of the field that can be expressed BLOB-- for storing binary large files Time and Date: Date-- represents 1000-1-1 ~ 9999-12-31 Time-- means 00:00:00 ~ 23:59:59 DateTime--1000-1-1 00:00:00 ~9999-12-31 23:59:59

to build a table statement:

CREATE TABLE Table name ( field 1 data type constraints , field 2 data type constraints , ... field n data type constraint ); Red Word, is fixed format, do not go to modify Case: Create Table Student ( Sid int PRIMARY KEY, Sname varchar () NOT NULL, Sex char (1), Brithdate Date )

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MySQL First lesson