- COUNT()函数
COUNT()函数返回匹配指定条件的行数
SQL COUNT(column_name) 语法
COUNT(column_name) 函数返回指定列的值的数目(NULL 不计入):
SELECT COUNT(column_name) FROM table_name;
示例:select count(brand_name) as num from sec_financial_product_shop_relate where shop_code=000055
SQL COUNT(*) 语法
COUNT(*) 函数返回表中的记录数:
SELECT COUNT(*) FROM table_name;
示例:select count(*) as num from sec_financial_product_shop_relate where shop_code=000055
SQL COUNT(DISTINCT column_name) 语法
COUNT(DISTINCT column_name) 函数返回指定列的不同值的数目:
SELECT COUNT(DISTINCT column_name) FROM table_name;
示例:select count(distinct brand_name) as num from sec_financial_product_shop_relate where shop_code=000055
注释:COUNT(DISTINCT) 适用于 ORACLE 和 Microsoft SQL Server,但是无法用于 Microsoft Access。
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SUM() 函数
SUM() 函数返回数值列的总数。
SQL SUM() 语法
SELECT SUM(column_name) FROM table_name;示例:SELECT SUM(score) AS nums FROM score_info where subject='语文';