How do I use regex in a SQLite query? - regex

I'd like to use a regular expression in sqlite, but I don't know how.
My table has got a column with strings like this: "3,12,13,14,19,28,32"
Now if I type "where x LIKE '3'" I also get the rows which contain values like 13 or 32,
but I'd like to get only the rows which have exactly the value 3 in that string.
Does anyone know how to solve this?

As others pointed out already, REGEXP calls a user defined function which must first be defined and loaded into the the database. Maybe some sqlite distributions or GUI tools include it by default, but my Ubuntu install did not. The solution was
sudo apt-get install sqlite3-pcre
which implements Perl regular expressions in a loadable module in /usr/lib/sqlite3/pcre.so
To be able to use it, you have to load it each time you open the database:
.load /usr/lib/sqlite3/pcre.so
Or you could put that line into your ~/.sqliterc.
Now you can query like this:
SELECT fld FROM tbl WHERE fld REGEXP '\b3\b';
If you want to query directly from the command-line, you can use the -cmd switch to load the library before your SQL:
sqlite3 "$filename" -cmd ".load /usr/lib/sqlite3/pcre.so" "SELECT fld FROM tbl WHERE fld REGEXP '\b3\b';"
If you are on Windows, I guess a similar .dll file should be available somewhere.

SQLite3 supports the REGEXP operator:
WHERE x REGEXP <regex>
http://www.sqlite.org/lang_expr.html#regexp

A hacky way to solve it without regex is where ',' || x || ',' like '%,3,%'

SQLite does not contain regular expression functionality by default.
It defines a REGEXP operator, but this will fail with an error message unless you or your framework define a user function called regexp(). How you do this will depend on your platform.
If you have a regexp() function defined, you can match an arbitrary integer from a comma-separated list like so:
... WHERE your_column REGEXP "\b" || your_integer || "\b";
But really, it looks like you would find things a whole lot easier if you normalised your database structure by replacing those groups within a single column with a separate row for each number in the comma-separated list. Then you could not only use the = operator instead of a regular expression, but also use more powerful relational tools like joins that SQL provides for you.

A SQLite UDF in PHP/PDO for the REGEXP keyword that mimics the behavior in MySQL:
$pdo->sqliteCreateFunction('regexp',
function ($pattern, $data, $delimiter = '~', $modifiers = 'isuS')
{
if (isset($pattern, $data) === true)
{
return (preg_match(sprintf('%1$s%2$s%1$s%3$s', $delimiter, $pattern, $modifiers), $data) > 0);
}
return null;
}
);
The u modifier is not implemented in MySQL, but I find it useful to have it by default. Examples:
SELECT * FROM "table" WHERE "name" REGEXP 'sql(ite)*';
SELECT * FROM "table" WHERE regexp('sql(ite)*', "name", '#', 's');
If either $data or $pattern is NULL, the result is NULL - just like in MySQL.

My solution in Python with sqlite3:
import sqlite3
import re
def match(expr, item):
return re.match(expr, item) is not None
conn = sqlite3.connect(':memory:')
conn.create_function("MATCHES", 2, match)
cursor = conn.cursor()
cursor.execute("SELECT MATCHES('^b', 'busy');")
print cursor.fetchone()[0]
cursor.close()
conn.close()
If regex matches, the output would be 1, otherwise 0.

With python, assuming con is the connection to SQLite, you can define the required UDF by writing:
con.create_function('regexp', 2, lambda x, y: 1 if re.search(x,y) else 0)
Here is a more complete example:
import re
import sqlite3
with sqlite3.connect(":memory:") as con:
con.create_function('regexp', 2, lambda x, y: 1 if re.search(x,y) else 0)
cursor = con.cursor()
# ...
cursor.execute("SELECT * from person WHERE surname REGEXP '^A' ")

I don't it is good to answer a question which was posted almost an year ago. But I am writing this for those who think that Sqlite itself provide the function REGEXP.
One basic requirement to invoke the function REGEXP in sqlite is
"You should create your own function in the application and then provide the callback link to the sqlite driver".
For that you have to use sqlite_create_function (C interface). You can find the detail from here and here

An exhaustive or'ed where clause can do it without string concatenation:
WHERE ( x == '3' OR
x LIKE '%,3' OR
x LIKE '3,%' OR
x LIKE '%,3,%');
Includes the four cases exact match, end of list, beginning of list, and mid list.
This is more verbose, doesn't require the regex extension.

UPDATE TableName
SET YourField = ''
WHERE YourField REGEXP 'YOUR REGEX'
And :
SELECT * from TableName
WHERE YourField REGEXP 'YOUR REGEX'

SQLite version 3.36.0 released 2021-06-18 now has the REGEXP command builtin.
For CLI build only.

Consider using this
WHERE x REGEXP '(^|,)(3)(,|$)'
This will match exactly 3 when x is in:
3
3,12,13
12,13,3
12,3,13
Other examples:
WHERE x REGEXP '(^|,)(3|13)(,|$)'
This will match on 3 or 13

You may consider also
WHERE x REGEXP '(^|\D{1})3(\D{1}|$)'
This will allow find number 3 in any string at any position

You could use a regular expression with REGEXP, but that is a silly way to do an exact match.
You should just say WHERE x = '3'.

If you are using php you can add any function to your sql statement by using: SQLite3::createFunction.
In PDO you can use PDO::sqliteCreateFunction and implement the preg_match function within your statement:
See how its done by Havalite (RegExp in SqLite using Php)

In case if someone looking non-regex condition for Android Sqlite, like this string [1,2,3,4,5] then don't forget to add bracket([]) same for other special characters like parenthesis({}) in #phyatt condition
WHERE ( x == '[3]' OR
x LIKE '%,3]' OR
x LIKE '[3,%' OR
x LIKE '%,3,%');

You can use the sqlean-regexp extension, which provides regexp search and replace functions.
Based on the PCRE2 engine, this extension supports all major regular expression features. It also supports Unicode. The extension is available for Windows, Linux, and macOS.
Some usage examples:
-- select messages containing number 3
select * from messages
where msg_text regexp '\b3\b';
-- count messages containing digits
select count(*) from messages
where msg_text regexp '\d+';
-- 42
select regexp_like('Meet me at 10:30', '\d+:\d+');
-- 1
select regexp_substr('Meet me at 10:30', '\d+:\d+');
-- 10:30
select regexp_replace('password = "123456"', '"[^"]+"', '***');
-- password = ***

In Julia, the model to follow can be illustrated as follows:
using SQLite
using DataFrames
db = SQLite.DB("<name>.db")
register(db, SQLite.regexp, nargs=2, name="regexp")
SQLite.Query(db, "SELECT * FROM test WHERE name REGEXP '^h';") |> DataFrame

for rails
db = ActiveRecord::Base.connection.raw_connection
db.create_function('regexp', 2) do |func, pattern, expression|
func.result = expression.to_s.match(Regexp.new(pattern.to_s, Regexp::IGNORECASE)) ? 1 : 0
end

Related

replace expression format xx-xx-xxxx_12345678

IDENTIFIER
31-03-2022_13636075
01-04-2022_13650262
04-04-2022_13663174
05-04-2022_13672025
20220099001
11614491_R
10781198
00000000000
11283627_P
11614491_R
-1
how can i remove (only) the "XX-XX-XXXXX_" Part in certain values of a column in SSIS but WITHOUT affecting values that doesn't have this format? For example "21-05-2022_12345678" = "12345678" but the other values i don't want them affected. This are just examples of many rows from this column so i want only the ones that have this format to be affected.
SELECT REVERSE(substring(REVERSE('09-03-2022_13481330'),0,CHARINDEX('_',REVERSE('09-03-2022_13481330'),0)))
result
13481330
but this also affects others values.Also this is in ssms not ssis because i am not sure how to transform this expression in ssis code.
Update : Corrected code in SSIS goes as following:
(FINDSTRING(IDENTIFIER,"__-__-____[_]",1) == 1) ? SUBSTRING(IIDENTIFIER,12,LEN(IDENTIFIER) - 11) : IDENTIFIER
Do you have access to the SQL source? You can do this on the sql by using a LIKE and crafting a match pattern using the single char wildcard _ please see below example
DECLARE #Value VARCHAR(50) = '09-03-2022_13481330'
SELECT CASE WHEN #Value LIKE '__-__-____[_]%' THEN
SUBSTRING(#Value,12,LEN(#Value)-11) ELSE #Value END
Please see the Microsoft Documentation on LIKE and using single char wildcards
If you don't have access to the source SQL it gets a bit more tricky as you might need to use regex in a script task or maybe there is a expression you can apply

sqlite valid email input [duplicate]

I'd like to use a regular expression in sqlite, but I don't know how.
My table has got a column with strings like this: "3,12,13,14,19,28,32"
Now if I type "where x LIKE '3'" I also get the rows which contain values like 13 or 32,
but I'd like to get only the rows which have exactly the value 3 in that string.
Does anyone know how to solve this?
As others pointed out already, REGEXP calls a user defined function which must first be defined and loaded into the the database. Maybe some sqlite distributions or GUI tools include it by default, but my Ubuntu install did not. The solution was
sudo apt-get install sqlite3-pcre
which implements Perl regular expressions in a loadable module in /usr/lib/sqlite3/pcre.so
To be able to use it, you have to load it each time you open the database:
.load /usr/lib/sqlite3/pcre.so
Or you could put that line into your ~/.sqliterc.
Now you can query like this:
SELECT fld FROM tbl WHERE fld REGEXP '\b3\b';
If you want to query directly from the command-line, you can use the -cmd switch to load the library before your SQL:
sqlite3 "$filename" -cmd ".load /usr/lib/sqlite3/pcre.so" "SELECT fld FROM tbl WHERE fld REGEXP '\b3\b';"
If you are on Windows, I guess a similar .dll file should be available somewhere.
SQLite3 supports the REGEXP operator:
WHERE x REGEXP <regex>
http://www.sqlite.org/lang_expr.html#regexp
A hacky way to solve it without regex is where ',' || x || ',' like '%,3,%'
SQLite does not contain regular expression functionality by default.
It defines a REGEXP operator, but this will fail with an error message unless you or your framework define a user function called regexp(). How you do this will depend on your platform.
If you have a regexp() function defined, you can match an arbitrary integer from a comma-separated list like so:
... WHERE your_column REGEXP "\b" || your_integer || "\b";
But really, it looks like you would find things a whole lot easier if you normalised your database structure by replacing those groups within a single column with a separate row for each number in the comma-separated list. Then you could not only use the = operator instead of a regular expression, but also use more powerful relational tools like joins that SQL provides for you.
A SQLite UDF in PHP/PDO for the REGEXP keyword that mimics the behavior in MySQL:
$pdo->sqliteCreateFunction('regexp',
function ($pattern, $data, $delimiter = '~', $modifiers = 'isuS')
{
if (isset($pattern, $data) === true)
{
return (preg_match(sprintf('%1$s%2$s%1$s%3$s', $delimiter, $pattern, $modifiers), $data) > 0);
}
return null;
}
);
The u modifier is not implemented in MySQL, but I find it useful to have it by default. Examples:
SELECT * FROM "table" WHERE "name" REGEXP 'sql(ite)*';
SELECT * FROM "table" WHERE regexp('sql(ite)*', "name", '#', 's');
If either $data or $pattern is NULL, the result is NULL - just like in MySQL.
My solution in Python with sqlite3:
import sqlite3
import re
def match(expr, item):
return re.match(expr, item) is not None
conn = sqlite3.connect(':memory:')
conn.create_function("MATCHES", 2, match)
cursor = conn.cursor()
cursor.execute("SELECT MATCHES('^b', 'busy');")
print cursor.fetchone()[0]
cursor.close()
conn.close()
If regex matches, the output would be 1, otherwise 0.
With python, assuming con is the connection to SQLite, you can define the required UDF by writing:
con.create_function('regexp', 2, lambda x, y: 1 if re.search(x,y) else 0)
Here is a more complete example:
import re
import sqlite3
with sqlite3.connect(":memory:") as con:
con.create_function('regexp', 2, lambda x, y: 1 if re.search(x,y) else 0)
cursor = con.cursor()
# ...
cursor.execute("SELECT * from person WHERE surname REGEXP '^A' ")
I don't it is good to answer a question which was posted almost an year ago. But I am writing this for those who think that Sqlite itself provide the function REGEXP.
One basic requirement to invoke the function REGEXP in sqlite is
"You should create your own function in the application and then provide the callback link to the sqlite driver".
For that you have to use sqlite_create_function (C interface). You can find the detail from here and here
An exhaustive or'ed where clause can do it without string concatenation:
WHERE ( x == '3' OR
x LIKE '%,3' OR
x LIKE '3,%' OR
x LIKE '%,3,%');
Includes the four cases exact match, end of list, beginning of list, and mid list.
This is more verbose, doesn't require the regex extension.
UPDATE TableName
SET YourField = ''
WHERE YourField REGEXP 'YOUR REGEX'
And :
SELECT * from TableName
WHERE YourField REGEXP 'YOUR REGEX'
SQLite version 3.36.0 released 2021-06-18 now has the REGEXP command builtin.
For CLI build only.
Consider using this
WHERE x REGEXP '(^|,)(3)(,|$)'
This will match exactly 3 when x is in:
3
3,12,13
12,13,3
12,3,13
Other examples:
WHERE x REGEXP '(^|,)(3|13)(,|$)'
This will match on 3 or 13
You may consider also
WHERE x REGEXP '(^|\D{1})3(\D{1}|$)'
This will allow find number 3 in any string at any position
You could use a regular expression with REGEXP, but that is a silly way to do an exact match.
You should just say WHERE x = '3'.
If you are using php you can add any function to your sql statement by using: SQLite3::createFunction.
In PDO you can use PDO::sqliteCreateFunction and implement the preg_match function within your statement:
See how its done by Havalite (RegExp in SqLite using Php)
In case if someone looking non-regex condition for Android Sqlite, like this string [1,2,3,4,5] then don't forget to add bracket([]) same for other special characters like parenthesis({}) in #phyatt condition
WHERE ( x == '[3]' OR
x LIKE '%,3]' OR
x LIKE '[3,%' OR
x LIKE '%,3,%');
You can use the sqlean-regexp extension, which provides regexp search and replace functions.
Based on the PCRE2 engine, this extension supports all major regular expression features. It also supports Unicode. The extension is available for Windows, Linux, and macOS.
Some usage examples:
-- select messages containing number 3
select * from messages
where msg_text regexp '\b3\b';
-- count messages containing digits
select count(*) from messages
where msg_text regexp '\d+';
-- 42
select regexp_like('Meet me at 10:30', '\d+:\d+');
-- 1
select regexp_substr('Meet me at 10:30', '\d+:\d+');
-- 10:30
select regexp_replace('password = "123456"', '"[^"]+"', '***');
-- password = ***
In Julia, the model to follow can be illustrated as follows:
using SQLite
using DataFrames
db = SQLite.DB("<name>.db")
register(db, SQLite.regexp, nargs=2, name="regexp")
SQLite.Query(db, "SELECT * FROM test WHERE name REGEXP '^h';") |> DataFrame
for rails
db = ActiveRecord::Base.connection.raw_connection
db.create_function('regexp', 2) do |func, pattern, expression|
func.result = expression.to_s.match(Regexp.new(pattern.to_s, Regexp::IGNORECASE)) ? 1 : 0
end

RegEx in a PHP mysqli prepared statement query to update numbers (integers) only

I'm using RegEx in a MySQLi prepared statement to find any rows that contain only an integer in a particular field. I want to replace those integers with an empty string. I also want to ignore any rows that contain alphabetic characters in that field. However, my syntax seems to be wrong. Here is my PHP code:
$Empty = "";
$IntegersOnly = "[0-9]+";
$stmt = mysqli_prepare($db, "UPDATE MyTable set MyField = ? where REGEXP ?");
$bind = mysqli_stmt_bind_param($stmt, "ss", $Empty, $IntegersOnly);
$exec = mysqli_stmt_execute($stmt);
I'm getting the following error at the bind line: mysqli_stmt_bind_param() expects parameter 1 to be mysqli_stmt, boolean given
So I believe my $stmt or $bind syntax is wrong.
Please consider that my programming experience is limited. I am hoping to use MySQLi (not PDO) and procedural programming (not OOP).
I'm using PHP 7 with a recent version of MariaDB, which is equivalent to MySQL
My apologies. I found the mistake. I should have used this:
$stmt = mysqli_prepare($db, "UPDATE MyTable set MyField = ? where MyField REGEXP ?");
In other words, I accidentally omitted MyField before REGEXP.

How do I get sqlite3 to do regexp in Tcl

I'd like to include regexp in my Tcl project but when I run my code I get this error:
no such function: REGEXP
my code looks like this:
return [brain eval "select * from bad WHERE input REGEXP '^(.){0}_'"]
I can test this exact code out in the database (I'm using BD browser for SQLite to browse the database) and it works correctly:
select * from uniq WHERE input REGEXP '^(.){1}0'
20 Rows returned from: select * from uniq WHERE input REGEXP
'^(.){1}0' (took 18ms)
So REGEXP will work in the browser, but not in my Tcl Script. Here's what I found so far on this issue:
someone else had the same problem in ruby: How to turn on REGEXP in SQLite3 and Rails 3.1?
Somone had the same problem in iOS and had to cretae_sqlite_function "No such function: REGEXP" in sqlite3 on iOS
how to write a function in sqlite: https://www.sqlite.org/c3ref/create_function.html
How to write a function for sqlite in Tcl:
https://www.sqlite.org/tclsqlite.html
An example of the function I may have to write in ruby:
https://github.com/sei-mi/sqlite3_ar_regexp/blob/master/lib/sqlite3_ar_regexp/extension.rb
REGEXP user function is not defined by default:
http://www.sqlite.org/lang_expr.html#regexp
A PHP example of the REGEXP user-defined Function:
How do I use regex in a SQLite query?
So I've come to the conclusion that I have to write some kind of function myself to get this to work, but I don't know what that function has to look like. Is it simply passing on the regular expression I make to sqlite3? or is it converting the regular expression to something else then passing it on?
Would the function look something like this?
file mkdir db
sqlite3 db ./brain/brain.sqlite -create true
db eval { create_function('regexp', 2) do |func, pattern, expression|
func.result = expression.to_s.match(
Regexp.new(pattern.to_s, Regexp::IGNORECASE)) ? 1 : 0
end
}
Thanks for any help or advice you can offer me!
It's actually pretty simple to enable regular expression processing. All you have to do (assuming that db is your connection handle) is use the function method like this:
db function regexp -deterministic {regexp --}
This tells SQLite to create the function, that it is deterministic (as regular expression matching most certainly is) and that it should work by passing the arguments to regexp -- (the -- stops REs that begin with - from causing problems).
See for yourself from this session log:
% package require sqlite3
3.8.10.2
% sqlite3 db :memory:
% db eval {select 1 where 'abc' regexp 'b'}
no such function: regexp
% db function regexp -deterministic {regexp --}
% db eval {select 1 where 'abc' regexp 'b'}
1

How to find all the source lines containing desired table names from user_source by using 'regexp'

For example we have a large database contains lots of oracle packages, and now we want to see where a specific table resists in the source code. The source code is stored in user_source table and our desired table is called 'company'.
Normally, I would like to use:
select * from user_source
where upper(text) like '%COMPANY%'
This will return all words containing 'company', like
121 company cmy
14 company_id, idx_name %% end of coding
453 ;companyname
1253 from db.company.company_id where
989 using company, idx, db_name,
So how to make this result more intelligent using regular expression to parse all the source lines matching a meaningful table name (means a table to the compiler)?
So normally we allow the matched word contains chars like . ; , '' "" but not _
Can anyone make this work?
To find company as a "whole word" with a regular expression:
SELECT * FROM user_source
WHERE REGEXP_LIKE(text, '(^|\s)company(\s|$)', 'i');
The third argument of i makes the REGEXP_LIKE search case-insensitive.
As far as ignoring the characters . ; , '' "", you can use REGEXP_REPLACE to suck them out of the string before doing the comparison:
SELECT * FROM user_source
WHERE REGEXP_LIKE(REGEXP_REPLACE(text, '[.;,''"]'), '(^|\s)company(\s|$)', 'i');
Addendum: The following query will also help locate table references. It won't give the source line, but it's a start:
SELECT *
FROM user_dependencies
WHERE referenced_name = 'COMPANY'
AND referenced_type = 'TABLE';
If you want to identify the objects that refer to your table, you can get that information from the data dictionary:
select *
from all_dependencies
where referenced_owner = 'DB'
and referenced_name = 'COMPANY'
and referenced_type = 'TABLE';
You can't get the individual line numbers from that, but you can then either look at user_source or use a regexp on the specific source code, which woudl at least reduce false positives.
SELECT * FROM user_source
WHERE REGEXP_LIKE(text,'([^_a-z0-9])company([^_a-z0-9])','i')
Thanks #Ed Gibbs, with a little trick this modified answer could be more intelligent.