mysql select * from table where not null

Question

是否可以從表中選擇*其中不爲空？

本質上我想要一個表的所有結果，但如果一列有一個空值的行我不希望在我的輸出文件，這是一個csv文件中看到空？

Answer 1

如果您group_concat一堆列，並且其中任何一列包含null，那麼結果爲空。因此，您可以使用此特性與從information_schema列收集的列名一起構建準備好的語句。

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; 

結果

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