trim() is used to clear all the whitespaces. Now, instead of clearing white spaces, I want to eleminate all special characters from the 'username'. Is there any function like trim() for eliminating special characters??
My sql query is like
Select value from table_name where trim(username) = 'ABCD'
and it returns null value. But there are some values related to 'ABCD' and it displays all the entries when i execute the query
select value from table_name where username like '%ABCD%'
there are nothing else like visible in 'username' field. Is there any solution for this?
MySQL does not have such kind of functionality to remove special characters. Instead you can use replace function (if you know what are special characters).
replace("your column name",'_','')
See example :
Select value from table_name where REPLACE(trim(username$),"$","");
this if you want to replace the $ with an empty char
Try this function:
Create Function [dbo].[RemoveNonAlphaCharacters](#Temp VarChar(1000))
Returns VarChar(1000)
AS
Begin
Declare #KeepValues as varchar(50)
Set #KeepValues = '%[^a-z]%'
While PatIndex(#KeepValues, #Temp) > 0
Set #Temp = Stuff(#Temp, PatIndex(#KeepValues, #Temp), 1, '')
Return #Temp
End
Call it like this:
Select dbo.RemoveNonAlphaCharacters('abc1234def5678ghi90jkl')
Once you understand the code, you should see that it is relatively simple to change it to remove other characters, too. You could even make this dynamic enough to pass in your search pattern.
refer this link:https://stackoverflow.com/a/22684392/3242978
Related
So I have a 625 digit long number to store in MySQL containing only 0 1 and 2 digits. The best way I've found to store it so far is as VARCHAR(625). I suspect that there are better ways to do it, I'm just not sure how.
I want to run a query such as "change the 128th character of the text to 1" without having to query the text into PHP, change it from there, and write the new text into the DB.
So the question is: what's the simplest method of doing this, and what field type is optimal for this kind of stuff?
Thanks in advance.
If you're going to be doing things like "change the 128th character of the text to 1" then I'd recommend keeping the data type as VARCHAR(625). If the length will always be 625 then you could use CHAR.
This will change the 128th character to 1 in MySQL:
UPDATE your_table set your_column =
CONCAT(SUBSTRING(your_column, 1, 127), '1', SUBSTRING(your_column, 129))
You can user INSERT() String function
give it a try
UPDATE tbl set field = INSERT(field,128,1,'1') where id = primary key
If you're only storing numbers, why not use int(625) instead of varchar?
You can use a replace command, but you'll have to know what to replace with
update TABLE_NAME set FIELD_NAME = replace(FIELD_NAME, ‘find this string’, ‘replace found string with this string’);
If you don't know what exactly you're replace with, you can replace the "replace found string with this string" with a sub query. Using length and substr to split, replace what you want, and concat back together.
This example should make what I'm saying make more sense
http://sqlfiddle.com/#!2/dbc21/2/0quey
A complex alternative:
Replacing 5th character to 'r' where primary key is 30:
update `myTable` set `myField`= regexp_replace(`myField`, '.', 'r', 5, 1) where `id`=30 limit 1
Hopefully I'm going about this the right way, if not I'm more than open to learning how this could be done better.
I need to pass a comma separated list of integers (always positive integers, no decimals) to a stored procedure. The stored procedure would then use the integers in an IN operator of the WHERE clause:
WHERE [PrimaryKey] IN (1,2,4,6,212);
The front-end is PHP and connection is made via ODBC, I've tried wrapping the parameter in single quotes and filtering them out in the stored procedure before the list gets to the query but that doesn't seem to work.
The error I'm getting is:
Conversion failed when converting the varchar value '1,2,4,6,212' to data type int.
I've never done this before and research so far has yielded no positive results.
Firstly, let's use a SQL Function to perform the split of the delimited data:
CREATE FUNCTION dbo.Split
(
#RowData nvarchar(2000),
#SplitOn nvarchar(5)
)
RETURNS #RtnValue table
(
Id int identity(1,1),
Data nvarchar(100)
)
AS
BEGIN
Declare #Cnt int
Set #Cnt = 1
While (Charindex(#SplitOn,#RowData)>0)
Begin
Insert Into #RtnValue (data)
Select
Data = ltrim(rtrim(Substring(#RowData,1,Charindex(#SplitOn,#RowData)-1)))
Set #RowData = Substring(#RowData,Charindex(#SplitOn,#RowData)+1,len(#RowData))
Set #Cnt = #Cnt + 1
End
Insert Into #RtnValue (data)
Select Data = ltrim(rtrim(#RowData))
Return
END
To use this, you would simply pass the function the delimited string as well as the delimiter, like this:
SELECT
*
FROM
TableName
WHERE
ColumnName IN (SELECT Data FROM dbo.Split(#DelimitedData, ','))
If you still have issues, due to the datatype, try:
SELECT
*
FROM
TableName
WHERE
ColumnName IN (SELECT CONVERT(int,Data) FROM dbo.Split(#DelimitedData, ','))
You can pass a comma separate list of values. However, you cannot use them as you like in an in statement. You can do something like this instead:
where ','+#List+',' like '%,'+PrimaryKey+',%'
That is, you like to see if the value is present. I'm using SQL Server syntax for concatenation because the question is tagged Microsoft.
My database contains empty table columns.
I would like to add a character like § to these empty rows so that I can search for them easier. How would I go about?
I already have a script that lets me replace or remove characters but I dont know a way to specify that rows that are empty should be updated with a character.
First, you probably don't have empty rows but empty column values in the rows. Wouldn't it be better if you just do it like if (!empty($row['column'])) instead of trying to put some bogus character?
Or if you want to do a SELECT just do something like this:
SELECT * FROM table_name WHERE column_name > ''; // seems to work for both NULL and empty string
Or:
DELETE FROM table_name WHERE column_name IS NULL or column_name = '';
UPDATE `table` SET column = "§" WHERE column = "";
It's bad to add character to an empty column because you are only adding extra size to the database. It's easy to search empty string on the database. Possible solutions of searching will be using of IS NULL to search for null columns.
SELECT * FROM tableName WHERE collName IS NULL
Another is by using CHAR_LENGTH (which gets the length of the data in the column)
SELECT * FROM tableName WHERE CHAR_LENGTH(collName) = 0
or by simply comparing it to ''
SELECT * FROM tableName WHERE colName = ''
What I've been trying to do is to select a row from a table while treating the varchar cells as int ones,
Here's a little explanation:
I have a table of phone numbers, some have "-" in them, some don't.
I wanted to select a number from the database, without including those "-" in the query.
So I used this preg_replace function:
$number = preg_replace("/[^0-9]/","",$number); //that leaves only the numbers in the variable
and then I run the following query:
"SELECT * FROM `contacts` WHERE `phone` = '{$number}'"
Now, of course it won't match sometimes since the number Im searching may have "-" in the database, so I tried to look for a solution,
on solution is just converting the cells into int's, but I'm not interested in doing that,
So after looking around, I found a MySQL function named CAST, used like : CAST(phone AS UNSIGNED)
I tried to mess with it, but it didn't seem to work.
Edit:
I kept looking around for a solution, and eventually used MySQL's REPLACE function for that.
"SELECT * FROM `contacts` WHERE REPLACE(phone,'-','') = '{$number}'"
Thank you all for your help.
MySQL doesn’t support extraction of regex matches.
You could try writing a stored function to handle it, but your best bet is to convert the data to ints so that all the numbers are uniform. I know you said you don't want to do that, but if you can, then it’s the best thing to do. Otherwise, you could do something like:
"SELECT * FROM `contacts` WHERE `phone` = '{$number}' OR `phone` = '{$number_with_dashes}'"
That is, search for the plain number OR the number with dashes.
1.
The easiest way to do it might be by using the REPLACE operator.
SELECT * FROM `contacts` WHERE REPLACE(REPLACE(`phone`, '-', ''), ' ', '') = '5550100';
What it does is simpy replacing all whitespaces and dashes with nothing, namely removing all spaces and dashes.
2.
Another alternative to solve the problem would be to use LIKE. If the phone numbers with a dash always are formatted the same way like 555-0100 and 555-0199 you can simple insert a %-sign instead of the dash. If your number may be formatted in different ways you can insert a %-between every character. It's not a beautiful solution but it does the trick.
SELECT * FROM `contacts` WHERE `phone` LIKE '555%0100';
or
SELECT * FROM `contacts` WHERE `phone` LIKE '5%5%5%0%1%0%0';
3.
You can use regular expressions. Since MySQL doesn't implement regex replace functions you need to use user defined functions. Have a look at https://launchpad.net/mysql-udf-regexp. It supports REGEXP_LIKE, REGEXP_SUBSTR, REGEXP_INSTR and REGEXP_REPLACE.
Edit: Removed my first answer and added some other alternatives.
I kept looking around for a solution, and eventually used MySQL's REPLACE function for that.
"SELECT * FROM `contacts` WHERE REPLACE(phone,'-','') = '{$number}'"
I'm having trouble with the sql below. Basically I have rows that contains strings according to the format: 129&c=cars. I only want the digits part, e.g. 129. The sql query is:
$result = mysql_query("SELECT * FROM " . $db_table . " WHERE id LIKE '" . $id . "%'");
Why doesn't % work? I can't use %...% because it catches too much.
I would actually recommend using regular expressions fo the matching, but unfortunately, there is no way to capture the matching part with mysql. You will have to do the extraction in php. If you have an array containing all the results called $array:
$array = preg_replace('/^(\d+).*/', '$1', $array);
You can use the MySQL 'regexp' stuff in the WHERE clause to reduce the amount of data retrieved to just the rows you want. The basic for of your query would look like:
SELECT * FROM table WHERE field REGEXP '^$id&'
where $id is inserted by PHP and the data you want is always at the start of the field and followed by a &. If not, adjust the regex to suit, of course.
MySQL's regex engine can't do capturing, unfortunately, so you'll still have to do some parsing in PHP as soulmerge showed above, but with the 'where regexp' stuff in MySQL, you'll only have to deal with rows you know contain the data you want, not the entire table.
Using a query like this:
SELECT *
FROM mytable
WHERE id >= '0' COLLATE UTF8_BIN
AND id < ':' COLLATE UTF8_BIN
will return all strings that start with a digit and make your expression sargable, i. e. and index on id can be used.
This will make your query run faster.