MySQL SELECT语句用于从MySQL中的一个或多个表中检索记录。
在本教程中,将通过语法和示例说明如何使用MySQL SELECT语句。
MySQL的SELECT语句的完整语法是:
SELECT
[
ALL
|
DISTINCT
| DISTINCTROW ]
[ HIGH_PRIORITY ]
[ STRAIGHT_JOIN ]
[ SQL_SMALL_RESULT | SQL_BIG_RESULT ] [ SQL_BUFFER_RESULT ]
[ SQL_CACHE | SQL_NO_CACHE ]
[ SQL_CALC_FOUND_ROWS ]
expressions
FROM
tables
WHERE
conditions]
GROUP
BY
expressions]
HAVING
condition]
ORDER
expression [
ASC
DESC
]]
[LIMIT [offset_value] number_rows | LIMIT number_rows OFFSET offset_value]
PROCEDURE
procedure_name]
INTO
[ OUTFILE
'file_name'
options
| DUMPFILE
| @variable1, @variable2, ... @variable_n]
FOR
UPDATE
| LOCK
IN
SHARE MODE];
里面有很多关键词。
一般我们都先用MySQL中SELECT语句语法中最简单的形式:
conditions];
然后再根据需要添加相应的关键词。
在语法中,中括号[]括起来的都是可选的
*
orderdetails
quantity >= 20
quantity
;
orderid, quantity, unitprice
quantity < 300
, unitprice
orders.OrderID, customers.CompanyName
customers
INNER
JOIN
orders
ON
customers.CustomerID = orders.CustomerID
OrderID;
OrderID, Quantity, UnitPrice
Quantity < 500
Quantity
OUTFILE
'results.txt'
FIELDS TERMINATED
','
OPTIONALLY ENCLOSED
'"'
LINES TERMINATED
'\n'
在INTO OUTFILE 'filename' options中的options可以指定为以下值
FIELDS ESCAPED BY 'character'FIELDS TERMINATED BY 'character' [ OPTIONALLY ENCLOSED BY 'character' ]LINES TERMINATED BY 'character'
character是某一个字符,比如 逗号,, 分号;等
ESCAPED表示转义TERMINATED表示分隔ENCLOSED表示封装 (比如字段的值本身带有 逗号,, 那么就需要封装起来)
原文链接:https://codingdict.com/