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SQL 函数

时间:2020-07-08 14:29:52      阅读:57      评论:0      收藏:0      [点我收藏+]

1.ucase()——把字段的值转换为大写

2.lcase()——把字段的值转换为小写

3.mid()——从文本字段中提取字符

SELECT MID(column_name,start[,length]) FROM table_name
column_name 必需。要提取字符的字段。
start 必需。规定开始位置(起始值是 1)。
length 可选。要返回的字符数。如果省略,则 MID() 函数返回剩余文本。

4.len()——返回文本字段中的长度

5.round()——把数值字段舍入为指定的小数位

SELECT ROUND(column_name,decimals) FROM table_name
column_name 必需。要舍入的字段。
decimals 必需。规定要返回的小数位数。

6.NOW ()——返回当前的日期和时间。

7.format()——对字段的显示进行格式化

SELECT FORMAT(column_name,format) FROM table_name
column_name 必需。要格式化的字段。
format 必需。规定格式。

总结:

AND / OR SELECT column_name(s)
FROM table_name
WHERE condition
AND|OR condition
ALTER TABLE (add column) ALTER TABLE table_name
ADD column_name datatype
ALTER TABLE (drop column) ALTER TABLE table_name
DROP COLUMN column_name
AS (alias for column) SELECT column_name AS column_alias
FROM table_name
AS (alias for table) SELECT column_name
FROM table_name  AS table_alias
BETWEEN SELECT column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2
CREATE DATABASE CREATE DATABASE database_name
CREATE INDEX CREATE INDEX index_name
ON table_name (column_name)
CREATE TABLE CREATE TABLE table_name
(
column_name1 data_type,
column_name2 data_type,
.......
)
CREATE UNIQUE INDEX CREATE UNIQUE INDEX index_name
ON table_name (column_name)
CREATE VIEW CREATE VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition
DELETE FROM DELETE FROM table_name
(Note: Deletes the entire table!!)

or

DELETE FROM table_name
WHERE condition

DROP DATABASE DROP DATABASE database_name
DROP INDEX DROP INDEX table_name.index_name
DROP TABLE DROP TABLE table_name
GROUP BY SELECT column_name1,SUM(column_name2)
FROM table_name
GROUP BY column_name1
HAVING SELECT column_name1,SUM(column_name2)
FROM table_name
GROUP BY column_name1
HAVING SUM(column_name2) condition value
IN SELECT column_name(s)
FROM table_name
WHERE column_name
IN (value1,value2,..)
INSERT INTO INSERT INTO table_name
VALUES (value1, value2,....)

or

INSERT INTO table_name
(column_name1, column_name2,...)
VALUES (value1, value2,....)

LIKE SELECT column_name(s)
FROM table_name
WHERE column_name
LIKE pattern
ORDER BY SELECT column_name(s)
FROM table_name
ORDER BY column_name [ASC|DESC]
SELECT SELECT column_name(s)
FROM table_name
SELECT * SELECT *
FROM table_name
SELECT DISTINCT SELECT DISTINCT column_name(s)
FROM table_name
SELECT INTO
(used to create backup copies of tables)
SELECT *
INTO new_table_name
FROM original_table_name

or

SELECT column_name(s)
INTO new_table_name
FROM original_table_name

TRUNCATE TABLE
(deletes only the data inside the table)
TRUNCATE TABLE table_name
UPDATE UPDATE table_name
SET column_name=new_value
[, column_name=new_value]
WHERE column_name=some_value
WHERE SELECT column_name(s)
FROM table_name
WHERE condition

 

SQL 函数

原文:https://www.cnblogs.com/qijiujiu/p/13266481.html

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