Question

I am glad if any one could help me out here.

I have a table Table1 and column XXXXXX with the data as following

XXXXXX
---------
1
2
1
2
x_y
A_12
3
12345_abcd

I want the output as

XXXXXX
---------
1
2
3

I have tried the following query

select DISTINCT XXXXXX from Table1 where XXXXXX NOT LIKE '%_%';

Also tried SELECT DISTINCT XXXXXX FROM Table1 WHERE CHAR ('_','XXXXXX')=0;

The above query is fetching everything from the table. Can anyone help me on this issue.

Answer 1

Try:

WHERE  XXXXXX NOT LIKE '%\\_%' ESCAPE '\\' 

The “escape” character is what tells MySQL that the underscore is to be interpreted as literal underscore character, and not a wildcard. (In the LIKE expression, an underscore (_) is a wildcard that matches any single character, just as the percent (%) is a wildcard that matches zero, one or more characters.

Note that other characters can be used as the escape character; it doesn’t have to be the backslash. The backslash is itself an escape character in MySQL, so have a backslash recognized as the escape character for the LIKE, we have to use double backslashes “\\“. That makes MySQL recognize this as a single backslash character.

As an example, we can use the carat “^” character as the escape character, like this:

WHERE  XXXXXX NOT LIKE '%^_%' ESCAPE '^'

Similarly, the escape character can be used to search for a literal percent sign % using a LIKE operator like this:

WHERE foo LIKE '%\\%%' ESCAPE '\\'

(That will search for an occurrence of a percent sign character in foo.)

---

As an alternative to the NOT LIKE operator, we can use the ‘NOT REGEXP’ operator to exclude rows where foo contains an underscore character, like this:

WHERE foo NOT REGEXP '_'