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 = ''
Related
I have a PostgreSQL table with a text field with a default value of an empty string ('') that will be a list of tags. I am trying to update that field by appending a string using CONCAT, but it is not working. This is my SQL:
UPDATE pins SET tags = concat(tags, :tagString) WHERE id = :id
$tagString would look something like this: [5378]
Similar queries have worked like this:
UPDATE pins SET tags = :tagString WHERE id = :id
It seems that the problem is the concat function. What is wrong?
Any quick assistance will be highly appreciated. I've table row in mysql named as mob_categories, now data is being is saved as '|' separated for instance (cat 1|cat 2|cat 3 and so on. Now i need to get the value from another column in the same table if the input value matches.
for instance if the value is cat 1 i need to select the value from another column is named as deveice_token wherever it matches with 'cat 1'
I tried this code but its not working somehow
SELECT * from table_name where find_in_set('cat 1',mob_categories) <> 0
so i modified a bit with the following code but it works with only numeric value if the value exits in this format in this format (i.e) 1,2,3
$userNotification = $wpdb->get_results("SELECT * from table_name where 1 IN (mob_categories); ");
What's i'm missing specifically?
Since data in mob_categories are separated by | rather than by comma (,) so you need to make it compatible for FIND_IN_SET first.
So replace all the | by comma (,) first.
SELECT * from table_name where find_in_set('cat 1', REPLACE(mob_categories,'|',',')) > 0
How to search for a comma-separated string in a database table in mySQL.
Suppose, I have a string in variable $facilities='breakfast,dinner,lunch' and in my database I have a string saved in a field called facilities having values breakfast,dinner,clothing,lunch,hot water.
How do I get the row having values $facilities?
Work like this i hope this is your requirement
select * from table where field_name like '%$fieldname%'
You're going to need to break apart the comma separated string first, and include a clause for each, so for that input you'd generate SQL like (assuming you want rows that have all three, and maybe other flags set):
SELECT *
FROM YourTable
WHERE FIND_IN_SET('breakfast', facilities)
AND FIND_IN_SET('dinner', facilities)
AND FIND_IN_SET('lunch', facilities)
You can break the string apart in PHP with something a little like:
$facilities='breakfast,dinner,lunch';
$desired = explode ( "," , $facilities );
And just use a loop to build your SQL
SELECT *
FROM tableName
WHERE FIND_IN_SET('lunch', 'breakfast,dinner,lunch')
EDIT:
SELECT *
FROM tableName
WHERE FIND_IN_SET('lunch', food_column)
food_column is the name of the column where the string 'breakfast,dinner,lunch' is stored
trim() is used to clear all the whitespaces. Now, instead of clearing white spaces, I want to eleminate all special characters from the 'username'. Is there any function like trim() for eliminating special characters??
My sql query is like
Select value from table_name where trim(username) = 'ABCD'
and it returns null value. But there are some values related to 'ABCD' and it displays all the entries when i execute the query
select value from table_name where username like '%ABCD%'
there are nothing else like visible in 'username' field. Is there any solution for this?
MySQL does not have such kind of functionality to remove special characters. Instead you can use replace function (if you know what are special characters).
replace("your column name",'_','')
See example :
Select value from table_name where REPLACE(trim(username$),"$","");
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
I have some rows ( > 50.000) in my database which contains columns with strings + '\n'. I mean the records looks like this:
abcd\n or \nabcd
Because of that sometimes my application does not work correctly. My question is: How could i update this rows with the correct value and eliminate '\n' spaces besides going to every row and update it manually ?
update your_table set somecolumn = replace(somecolumn, '\n', '')
update mytable SET title = TRIM(TRAILING '\n' FROM title)
Have you tried this?
UPDATE table SET column=REPLACE(column,'\\n','') WHERE column LIKE '%\\n' OR column LIKE '\\n%'
If you don't know where the new line is, simply:
UPDATE table SET column=REPLACE(column,'\\n','')