mysql select * from table where not null

Question

是否可以从表中选择*其中不为空？

本质上我想要一个表的所有结果，但如果一列有一个空值的行我不希望在我的输出文件，这是一个csv文件中看到空？

Answer 1

如果您group_concat一堆列，并且其中任何一列包含null，那么结果为空。因此，您可以使用此特性与从information_schema列收集的列名一起构建准备好的语句。

drop table if exists t; 
create table t (tID int, Name varchar(20), Type varchar(20), Start_Date date, End_Date date); 
insert into t values 
(1, null , 'Retail' , '2010-01-01', '2010-07-21'), 
(1, 'Cust_1' , null , '2010-07-22', '2012-05-17'), 
(1, 'Cust_1' , 'Corp' , '2012-05-18', '2012-12-31'); 



select group_concat(column_name) into @gc from information_schema.columns where table_name = 't' and table_schema = 'sandbox'; 
set @sqlstmt = concat('select * from t where concat(', @gc, ') is not null;'); 

#select @sqlstmt; 

prepare sqlstmt from @sqlstmt; 
execute sqlstmt; 
deallocate prepare sqlstmt; 

结果

+------+--------+------+------------+------------+ 
| tID | Name | Type | Start_Date | End_Date | 
+------+--------+------+------------+------------+ 
| 1 | Cust_1 | Corp | 2012-05-18 | 2012-12-31 | 
+------+--------+------+------------+------------+ 
1 row in set (0.00 sec)