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法律研究如何计算 MySQL 中具有特定值的列数量？
以下是语法 -
select sum(yourColumnName1+yourColumnName2+yourColumnName3...N) as `anyAliasName1`, sum(yourColumnName1 and yourColumnName2 and yourColumnName3….N) as anyAliasName from yourTableName;
我们来创建一张表 -
mysql> create table demo36 −> ( −> id int not null auto_increment primary key, −> value1 int, −> value2 int, −> value3 int −> ); Query OK, 0 rows affected (1.68 sec)
使用 insert 命令向表中插入一些记录 -
mysql> insert into demo36(value1,value2,value3) values(1,0,0); Query OK, 1 row affected (0.14 sec) mysql> insert into demo36(value1,value2,value3) values(1,0,1); Query OK, 1 row affected (0.11 sec) mysql> insert into demo36(value1,value2,value3) values(1,1,1); Query OK, 1 row affected (0.22 sec) mysql> insert into demo36(value1,value2,value3) values(0,1,0); Query OK, 1 row affected (0.12 sec) mysql> insert into demo36(value1,value2,value3) values(1,1,0); Query OK, 1 row affected (0.10 sec)
使用 select 语句从表中显示记录 -
mysql> select *from demo36;
这将生成以下输出 -
+----+--------+--------+--------+ | id | value1 | value2 | value3 | +----+--------+--------+--------+ | 1 | 1 | 0 | 0 | | 2 | 1 | 0 | 1 | | 3 | 1 | 1 | 1 | | 4 | 0 | 1 | 0 | | 5 | 1 | 1 | 0 | +----+--------+--------+--------+ 5 rows in set (0.00 sec)
以下是统计 MySQL 中特定值列数的查询 -
mysql> select −> sum(value1+value2+value3) as `Total_Number_Of_1`, −> sum(value1 and value2 and value3) as `Total_Number_Of_Rows_With_1` −> from demo36;
这将生成以下输出 -
+-------------------+-----------------------------+ | Total_Number_Of_1 | Total_Number_Of_Rows_With_1 | +-------------------+-----------------------------+ | 9 | 1 | +-------------------+-----------------------------+ 1 row in set (0.00 sec)
更新于：19-11-2020
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