How do I escape wildcards (_ and %) when using a SQL LIKE operator in Oracle?
I came to a silly issue today. I need to search for the presence of an underscore _ on a varchar column using LIKE. It doesn't work -- as expected -- since underscores are wildcards according to SQL. Here's my (simpified) code:
create table property (
name varchar(20),
value varchar(50)
);
insert into property (name, value) values ('port', '8120');
insert into property (name, value) values ('max_width', '90');
insert into property (name, value) values ('taxrate%', '5.20');
I tried the following queries in PostgreSQL and they return the rows I want:
select * from property where name like '%\_%'; -- should return: max_width
select * from property where name like '%\%%'; -- should return: taxrate%
Unfortunately it doesn't work in Oracle 12c. Is there a "standard" way of escaping wildcards? Or at least something that works in Oracle?
You can use the escape syntax
You can include the actual characters % or _ in the pattern by using the ESCAPE clause, which identifies the escape character. If the escape character precedes the character % or _ in the pattern, then Oracle interprets this character literally in the pattern rather than as a special pattern-matching character.
So you can do:
select * from property where name like '%\_%' escape '\';
NAME VALUE
-------------------- --------------------------------------------------
max_width 90
select * from property where name like '%\%%' escape '\';
NAME VALUE
-------------------- --------------------------------------------------
taxrate% 5.20
Related
I need to return the rows that contain both _1 and _2 from the SQL Server table. Below is my query and it returns the rows even both the above conditions are not matched.
As per my knowledge, I can use [ and ] to match multiple values when using the LIKE clause with wild cards.
DECLARE #TempTable AS TABLE (Col VARCHAR(MAX))
INSERT INTO #TempTable VALUES
('001098E2-5995-446F-87DC-BE71D2B30D37_2|69FA4BCD-C90B-4375-B08C-B3615C55500D_2'),
('0025F9BF-995D-4C88-BBD6-4C707A88BC32_1|F53668A8-F819-4309-BC0C-8DE4C2637419_2'),
('007BB00A-3B69-45FC-A265-1EC8B00E011A_2|0701649E-8BFE-4B03-8456-51E2D9169BD5_2|08950E50-80B2-4BDF-9FC7-3AB0AA4587AE_1')
SELECT * FROM #TempTable
WHERE (Col LIKE '%[_1]%' AND Col LIKE '%[_2]%')
I expect not to return 001098E2-5995-446F-87DC-BE71D2B30D37_2|69FA4BCD-C90B-4375-B08C-B3615C55500D_2, but SQL Server returns all 3 records.
Thanks in advance.
SELECT * FROM #TempTable
WHERE (Col LIKE '%[_]1%' AND Col LIKE '%[_]2%')
Using Wildcard Characters As Literals
You can use the wildcard pattern matching characters as literal characters. To use a wildcard character as a literal character, enclose the wildcard character in brackets. The following table shows several examples of using the LIKE keyword and the [ ] wildcard characters.
_ is also a wildcard matching one arbitrary character. You can define an ESCAPE character and escape it to match a regular underscore. You don't need [], i.e. character classes here.
SELECT *
FROM #temptable
WHERE col LIKE '%\_1%' ESCAPE '\'
AND col LIKE '%\_2%' ESCAPE '\';
db<>fiddle
You can use the wildcard pattern matching characters as literal characters.
To use a wildcard character as a literal character, enclose the wildcard character in brackets.
WHERE (Col LIKE '%[_]1%' AND Col LIKE '%[_]2%')
you can also escape the underscore like this
WHERE (Col LIKE '%$_1%' ESCAPE '$')
AND (Col LIKE '%$_2%' ESCAPE '$')
I have a table in SQL Server that stores codes. Depending on the nomenclature, some begin with 'DB_' and others with 'DBL_'. I need a way to filter the ones that start with 'DB_', since when I try to do it, it returns all the results.
CREATE TABLE CODES(Id integer PRIMARY KEY, Name Varchar(20));
INSERT INTO CODES VALUES(1,'DBL_85_RC001');
INSERT INTO CODES VALUES(2,'DBL_85_RC002');
INSERT INTO CODES VALUES(3,'DBL_85_RC003');
INSERT INTO CODES VALUES(4,'DB_20_SE_RC010');
INSERT INTO CODES VALUES(5,'DB_20_SE_RC011');
SELECT * FROM CODES where Name like 'DB_%';
The result that returns:
1|DBL_85_RC001
2|DBL_85_RC002
3|DBL_85_RC003
4|DB_20_SE_RC010
5|DB_20_SE_RC011
Expected result:
4|DB_20_SE_RC010
5|DB_20_SE_RC011
_ is a wildcard for a single character in a LIKE expression. Thus both 'DB_' and 'DBL' are LIKE 'DB_'. If you want a literal underscore you need to put it in brackets ([]):
SELECT *
FROM CODES
WHERE [Name] LIKE 'DB[_]%';
The underscore is a wildcard in SQL Server. You can escape it:
where name like 'DB$_%' escape '$'
You could also use left():
where left(name, 3) = 'DB_'
However, this is not index- and optimizer friendly.
I want to check a column for a special sign with regular expression, but not all special sign. I want all sign that are not letter, number and not ,+.-& (blank) .I try this
where column like '%[^((a-z)(A-Z)(0-9)(,\+\.\-)(\&)( ))]%'
same like this
where column like '%[^0-9a-zA-Z ,\-+\.\& ]%'
But if I try this Statement, I get strings with - and speziell blank.
result1: 't-est regex'
result2: ' TestJ. '
Have you any idea why?
Thx for the help.
The LIKE operator isn't exactly using the regex syntax.
It's way more simplified.
But some things are still possible.
This LIKE would get what you want:
where [column] like '%[^A-Za-z0-9 &.,+-]%'
Note that the class negation ^ does work.
And it's best to put a - at the end of a class. So it's not mistaken to be used for a range of characters.
There's no concept for capture groups in a LIKE, so the ( and ) were removed.
But if you also want the LIKE to ignore the brackets, just add them to the character class.
(even in regex you don't have capture groups inside a character class anyway)
The LIKE operation is case-insensitive when the COLLATION of the character field is case-insensitive.
Which seems to be the default on most databases.
So most of the times, a LIKE '%[A-Z]%' and LIKE '%[A-Za-z]%' would behave the same.
Example snippet:
-- using a Case-Sensitive collation for the varchar.
declare #T table (id int identity(1,1), col varchar(30) COLLATE Latin1_General_CS_AS);
insert into #T (col) values
('abc123'),
('ABC & 123'),
('abc123 &.,+-'),
('abc-123 #');
select * from #T where col like '%[^A-Za-z0-9 &.,+-]%';
Returns:
id col
-- ---------
4 abc-123 #
I wrote the below SQL query with a LIKE condition:
SELECT * FROM Manager
WHERE managerid LIKE '_%'
AND managername LIKE '%_%'
In the LIKE I want to search for any underscores %_%, but I know that my columns' data has no underscore characters.
Why does the query give me all the records from the table?
Sample data:
create table Manager(
id int
,managerid varchar(3)
,managername varchar(50)
);
insert into Manager(id,managerid,managername)values(1,'A1','Mangesh');
insert into Manager(id,managerid,managername)values(2,'A2','Sagar');
insert into Manager(id,managerid,managername)values(3,'C3','Ahmad');
insert into Manager(id,managerid,managername)values(4,'A4','Mango');
insert into Manager(id,managerid,managername)values(5,'B5','Sandesh');
Sql-Fiddle
Modify your WHERE condition like this:
WHERE mycolumn LIKE '%\_%' ESCAPE '\'
This is one of the ways in which Oracle supports escape characters. Here you define the escape character with the escape keyword. For details see this link on Oracle Docs.
The '_' and '%' are wildcards in a LIKE operated statement in SQL.
The _ character looks for a presence of (any) one single character. If you search by columnName LIKE '_abc', it will give you result with rows having 'aabc', 'xabc', '1abc', '#abc' but NOT 'abc', 'abcc', 'xabcd' and so on.
The '%' character is used for matching 0 or more number of characters. That means, if you search by columnName LIKE '%abc', it will give you result with having 'abc', 'aabc', 'xyzabc' and so on, but no 'xyzabcd', 'xabcdd' and any other string that does not end with 'abc'.
In your case you have searched by '%_%'. This will give all the rows with that column having one or more characters, that means any characters, as its value. This is why you are getting all the rows even though there is no _ in your column values.
The underscore is the wildcard in a LIKE query for one arbitrary character.
Hence LIKE %_% means "give me all records with at least one arbitrary character in this column".
You have to escape the wildcard character, in sql-server with [] around:
SELECT m.*
FROM Manager m
WHERE m.managerid LIKE '[_]%'
AND m.managername LIKE '%[_]%'
See: LIKE (Transact-SQL)
Demo
As you want to specifically search for a wildcard character you need to escape that
This is done by adding the ESCAPE clause to your LIKE expression. The character that is specified with the ESCAPE clause will "invalidate" the following wildcard character.
You can use any character you like (just not a wildcard character). Most people use a \ because that is what many programming languages also use
So your query would result in:
select *
from Manager
where managerid LIKE '\_%' escape '\'
and managername like '%\_%' escape '\';
But you can just as well use any other character:
select *
from Manager
where managerid LIKE '#_%' escape '#'
and managername like '%#_%' escape '#';
Here is an SQLFiddle example: http://sqlfiddle.com/#!6/63e88/4
Underscore is a wildcard for something.
for example
'A_%' will look for all match that Start whit 'A' and have minimum 1 extra character after that
In case people are searching how to do it in BigQuery:
An underscore "_" matches a single character or byte.
You can escape "\", "_", or "%" using two backslashes. For example, "\%". If you are using raw strings, only a single backslash is required. For example, r"\%".
WHERE mycolumn LIKE '%\\_%'
Source: https://cloud.google.com/bigquery/docs/reference/standard-sql/operators
You can write the query as below:
SELECT * FROM Manager
WHERE managerid LIKE '\_%' escape '\'
AND managername LIKE '%\_%' escape '\';
it will solve your problem.
If a field value in the table of SQL Server is like A(B) and if I to write a query
SELECT * FROM MyTable WHERE MyField = 'A(B)'
it is not returning any result. How to handle this situation?
Your query should work fine, if you want to specify a different escape parameter, you can use ESCAPE.
WHERE column LIKE '%A#(B#)%' ESCAPE '#'
Also, if you want to match anything that contains "A(B)", don't forget to surround it by percetages symbols.