Description of the role of MYSQL where 1=1 decision _mysql

So on the Internet

Check the check, here is a brief discussion:
1=1 forever True, 1<>1 forever false.

The use of 1<>1:
Used to take only the structure without data
For example:
CREATE TABLE Table_temp tablespace tbs_temp as
SELECT * FROM Table_ori where 1<>1
Build a table table_temp the same as the Table_ori structure, but don't table_ori the data. (except table structure, other knots

Structure as well)

The usefulness of 1=1
for dynamic SQL
For example lv_string: = ' Select Tbl_name,tbl_desc from tbl_test where 1=1 ' | | L_condition;
L_condition: = ' and tbl_name = ' abc ' When the user selects the queried name ' abc ';

L_condition is empty when you select a name query lv_string = ' Select Tbl_name,tbl_desc from Tbl_test

Where 1=1 ', there is no error in the operation, equal to the absence of a restricted name condition. But if there is no 1=1 condition, then lv_string =

' Select Tbl_name,tbl_desc from Tbl_test where ';

In addition to the 1=1 or 1<>1 other than the conditions of perpetual and permanent leave the same.