Is there an efficient way to limit the number of characters for a mysql query lookup? So, if a text column field had 18000 characters, but I only need to query 500 characters, is there a way to mysql_query("select text_column from random_table limit_char_count 500")?
How about using the SUBSTRING() function?
Below example selects 4 characters starting from 1st position
SELECT SUBSTRING(text_column,1,4)
FROM random_table
WHERE something = something else
EDIT - edited based on - for all forms of SUBSTRING(), the position of the first character in the string from which the substring is to be extracted is reckoned as 1.
Related
I have this column in a table which is comma delimited to separate the values.
Here's the sample data:
2003,2004
2003,2005
2003,2006
2003,2004,2005
2003,2007
I want to get all data that contains only 1 comma.
I've been playing around with the '%' and '_' wildcards, but I can't seem to get the results I need.
SELECT column FROM table WHERE column like '%_,%'
Replace the , with '' empty set then take the original length less the replaced length. if 1 then only 1 comma if > 1 then more than 1 comma.
The length difference would represent the number of commas.
Length(column) - length(Replace(column,',','')) as NumOfCommas
or
where Length(column) - length(Replace(column,',','')) =1
While this may solve the problem, I agree with what others have indicated. Storing multiple values in a single column in a RDBMS is asking for more trouble. Better to normalize the data and get it to at least 3rd Normal form!
You can also use find_in_set() method which searches a value in comma separated list, by picking the last value of column using substring_index we can then check result of find_in_set should be 2 so that its the second and last value from list
select *
from demo
where find_in_set(substring_index(data,',',-1),data) = 2
Demo
Maybe another solution is to use regular expression in your case it can look like this ^[0-9]{4},[0-9]{4}$ :
SELECT * FROM MyTable WHERE ColName REGEXP '^[0-9]{4},[0-9]{4}$'
Or if you want all non comma one or more time :
SELECT * FROM MyTable WHERE ColName REGEXP '^[^,]*,[^,]*$'
I need a SELECT query in MYSQL that will retrieve all rows in one table witch field values contain "?" char with one condition: the char is not the last character
Example:
ID Field
1 123??see
2 12?
3 45??78??
Returning rows would then be those from ID 1 and 3 that match the condition given
The only statement I have is:
SELECT *
FROM table
WHERE Field LIKE '%?%'
But, the MySQL query does not solve my problem..
The LIKE expressions also support a wildcard "_" which matches exactly one character.
So you can write an expression like the example below, and know that your "?" will not be the last character in the string. There must be at least one more character.
WHERE intrebare LIKE '%?_%'
Re comment from #JohnRuddell,
Yes, that's true, this will match the string "??" because a "?" exists in a position that is not the last character.
It depends whether the OP means for that to be a match or not. The OP says the string "45??78??" is a match, but it's not clear if they would intend that "4578??" to be a match.
An alternative is to use a regular expression, but this is a little more tricky because you have to escape a literal "?", so it won't be interpreted as a regexp metacharacter. Then also escape the escape character.
WHERE intrebare REGEXP '\\?[^?]'
you can just add an additional where where the last character is not a ?
SELECT *
FROM intrebari
WHERE intrebare LIKE '%?%' AND intrebare NOT LIKE '%?'
you could also do it like this
SELECT *
FROM intrebari
WHERE intrebare LIKE '%?%' AND RIGHT(intrebare,1) <> '?'
DEMO
Ok, so here is the issue.
I have a table with some columns and 'subject' is one of the columns.
I need to get the first 10 letters from the 'subject' field no matter the 'subject' field contains a string with 100 letters.
For example,
Table - tbl.
Columns - id, subject, value.
SQL Query:
SELECT subject FROM tbl WHERE id ='$id';
The result I am getting is, for example
Hello, this is my subject and how are you
I only require the first 10 characters
Hello, thi
I can understand that I can remove the rest of the characters using php substr() but that's not possible in my case. I need to get the excess characters removed by MySQL. How can this be done?
Using the below line
SELECT LEFT(subject , 10) FROM tbl
MySQL Doc.
SELECT SUBSTRING(subject, 1, 10) FROM tbl
Have a look at either Left or Substring if you need to chop it up even more.
Google and the MySQL docs are a good place to start - you'll usually not get such a warm response if you've not even tried to help yourself before asking a question.
I want to fetch all records which has one column contained % sign in mysql
we can do this using mysql using like
for ex..
select * from table where column like '%%';
it returns all records..
Please suggest
Use a backslash to escape the percent:
select * from table where column like '%\%%';
will match any row containing a percent character
% is a special character, try using escape characters to find it. Right now you're just telling mysql to look for a string using 2 wildcard characters (%) as opposed to the actual '%' character. Try using
select * from table where column = 'a%' ESCAPE 'a'
Basically telling mySQL to "Look for the string 'a%', but remove the char a in front of it.
EDIT: Another option is just using
select * from table where column = '\%'
Doing the same thing on later mySQL versions. The backslash is the "standard" escape character.
EDIT 2: Or to actually answer your question:
select * from table where column = '%\%%'
You need to escape the literal % sign with a \ e.g.
select * from table where column like '\%%';
I have an LINK field in my table. Some rows have a link, some don't.
I'd like to select all rows where LINK is present. (length is greater than X characters).
How do I write this?
How about:
SELECT * FROM sometable WHERE CHAR_LENGTH(LINK) > 1
Here's the MySql string functions page (5.0).
Note that I chose CHAR_LENGTH instead of LENGTH, as if there are multibyte characters in the data you're probably really interested in how many characters there are, not how many bytes of storage they take. So for the above, a row where LINK is a single two-byte character wouldn't be returned - whereas it would when using LENGTH.
Note that if LINK is NULL, the result of CHAR_LENGTH(LINK) will be NULL as well, so the row won't match.
select * from [tbl] where [link] is not null and len([link]) > 1
For MySQL user:
LENGTH([link]) > 1
Try:
SELECT
*
FROM
YourTable
WHERE
CHAR_LENGTH(Link) > x
Just in case anybody want to find how in oracle and came here (like me), the syntax is
select length(FIELD) from TABLE
just in case ;)