I know that I can use something like
select distinct left(table.column, 1) as firstChar
from table
In MySQL to return just the first character of a field.
The problem is I'm working with SQL Derby :( and it does not like this syntax.
Is there a way to perform this query using derby?
select substr(table.column,1,1)
from table
order by table.column
Related
I am trying to getting just the first two words on sql query, I am using the match: ^\w{2}- but with no success because nothing is coming to me, I need to get those values
BA, CE, DF, ES, GO, I don't know how can I do that, below some data example.
SC&Tipo=FM
SC&Tipo=Web
SC&Tipo=Comunitaria
RS&Tipo=Todas
RS&Tipo=AM
RS&Tipo=FM
RS&Tipo=Web
RS&Tipo=Comunitaria
BA-Salvador&Tipo=12horas
CE-Fortaleza&Tipo=12horas
CE-Interior&Tipo=12horas
DF-Brasilia&Tipo=12horas
ES-Interior&Tipo=12horas
ES-Vitoria&Tipo=12horas
GO-Goiania&Tipo=12horas
MG-ZonaDaMata/LestedeMinas&Tipo=12horas
MG-AltoParanaiba&Tipo=12horas
MG-BeloHorizonte&Tipo=12horas
MG-CentroOestedeMinas&Tipo=12horas
Query: SELECT * FROM tabel WHERE filter REGEXP '^\w{2}-'
EDIT SOLVED:
To solve the query should be:
SELECT SUBSTRING(column, 1, 2) AS column FROM table WHERE column REGEXP '^[[:alnum:]_]{2}-'
MySQL doesn't support the character class \w or \d. Instead of \w you have to use [[:alnum:]]. You can find all the supported character classes on the official MySQL documentation.
So you can use the following solution using REGEXP:
SELECT *
FROM table_name
WHERE filter REGEXP '^[[:alnum:]]{2}-'
You can use the following to get the result with regular expression too, using REGEXP_SUBSTR:
SELECT REGEXP_SUBSTR(filter, '^[[:alnum:]]{2}-')
FROM table_name
WHERE filter REGEXP '^[[:alnum:]]{2}-';
Or another solution using HAVING to filter the result:
SELECT REGEXP_SUBSTR(filter, '^[[:alnum:]]{2}-') AS colResult
FROM table_name
HAVING colResult IS NOT NULL;
To get the value before MySQL 8.0 you can use the following with LEFT:
SELECT LEFT(filter, 3)
FROM table_name
WHERE filter REGEXP '^[[:alnum:]]{2}-';
demo: https://www.db-fiddle.com/f/7mJEmCkEiYhCYK3PcEZTNE/0
Using SUBSTRING(<column>, 1, 2) should also work..
More or less like below
SELECT
<column>
, SUBSTRING(<column>, 1, 2)
FROM
<table>
WHERE
SUBSTRING(<column>, 1, 2) IN ('BA' [,<value>..])
Some things are BNF (Backus-Naur form) in the SQL code.
<..> means replace with what you need.
[, ..] means optional unlimited repeat the comma in there is part off SQL syntax
I was trying to query values in a table where they started with 'a', 'b' or 'c'. I know in MS SQL you can make a [charlist] to do this:
( LIKE '[abc]%' )
I was wondering what the correct syntax was in other databases such as Oracle or mySQL.
Thanks
In MySQL you can use Regular Expressions
where some_column REGEXP '[abc].*'
MySQL follows the same syntax. Use % to wildcard, or ? single characters:
SELECT * FROM `table` WHERE `column` LIKE 'a%' OR `column` LIKE 'b%'...
Alternatively, You can use REGEXP in MySQL, but it will cause performance hits as you are unable to use indexes in order to query data.
For the SELECT LIKE 'a%' query it will be able to use the index to lookup all items starting with A, and return them efficiently. Using REGEXP will cause a row scan for each item, and performance will be greatly impacted.
I was trying to solve a problem in SQL and I came across the problem:
Query the list of CITY names from STATION table that do not start with vowels. Your result cannot contain duplicates.
I used regexp_like() function using Oracle but how I can query the results using MySQL?
In Oracle I did regexp_like(city, '^[^aeiou]', 'i')
MySQL has a REGEXP keyword for just such an occasion.
SELECT ...
FROM ...
WHERE field REGEXP 'expression';
See: http://dev.mysql.com/doc/refman/5.7/en/regexp.html (first Google result for MySQL REGEXP)
Select distinct City
from Station
where Left(Upper(city),1))
not like '%[AEIOU]%'
There is table named Students. I want to extract the names of students whose name starts with either 'n' or 'p' or 'y'. I know that in TSQL (MS SQL server) I can write the query as follows and it works:
SELECT * FROM Students WHERE StudentName LIKE '[npy]%'
But when I execute the same query in MySQL (phpmyadmin) I was unable to retrieve the correct result set. I tried converting the letters of the student name into the same case which is mentioned in the charlist. I did bit of googling and found out that in MySQL we need to specify this as a regular expression. I executed the below query and got the expected result.
SELECT * FROM Students WHERE StudentName REGEXP '[[:<:]]n | [[:<:]]p | [[:<:]]y'
I want to know the reason why LIKE '[charlist]%' syntax is not working with MySQL. Is it due to the implementation in MySQL (MySQL doesn't support the syntax) or something wrong with the phpmyadmin version I'm using?
Any help regarding this is highly appreciated. Thanks :)
There is an even shorter way to write your query:
SELECT * FROM Students WHERE StudentName REGEXP '^[npy]'
And if you're concerned about being case sensitive:
SELECT * FROM Students WHERE StudentName REGEXP BINARY '^[npy]'
In MySQL, a REGEXP pattern match succeeds anywhere in the value, which differs from LIKE where the pattern must match the entire value.
The following link will give you a more complete answer:
MySQL Pattern Matching
MySQL :
Case insensitive: SELECT * FROM Students WHERE StudentName RLIKE '^[npy]' ;
Case sensitive : SELECT * FROM Students WHERE StudentName CAST(RLIKE as BINARY) '^[npy]' ;
I am trying to execute the sql query:
select * from table where column like '%value%';
But the data is saved as 'Value' ( V is capital ).
When I execute this query i don't get any rows.
How do i make the call such that, it looks for 'value' irrespective of the casing of the characters ?
use LOWER Function in both (column and search word(s)). Doing it so, you assure that the even if in the query is something like %VaLuE%, it wont matter
select qt.*
from query_table qt
where LOWER(column_name) LIKE LOWER('%vAlUe%');
If you want this column be case insensitive :
ALTER TABLE `schema`.`table`
CHANGE COLUMN `column` `column` TEXT CHARACTER SET 'utf8' COLLATE 'utf8_general_ci';
Thus, you don't have to change your query.
And the MySQL engine will process your query quicker than using lower() function or any other tricks.
And I'm not sure that using lower function will be a good solution for index searching performance.
Either use a case-insensitive collation on your table, or force the values to be lower case, e.g.
WHERE lower(column) LIKE lower('%value%');
Try using a case insensitive collation
select * from table
where column like '%value%' collate utf8_general_ci
Use the lower() function:
select t.*
from table t
where lower(column) like '%value%';
you should use either lower or upper function to ignore the case while you are searching for some field using like.
select * from student where upper(sname) like 'S%';
OR
select * from student where lower(sname) like 'S%';
If you are using PostgreSQL, a simpler solution is to use insensitive like (ILIKE):
SELECT * FROM table WHERE column ILIKE '%value%'
I know this is a very old question, but I'm posting this for posterity:
Non-binary string comparisons (including LIKE) are case-insensitive by default in MySql:
https://dev.mysql.com/doc/refman/en/case-sensitivity.html
This will eventually do the same thing. The ILIKE works, irrespective of the casing nature
SELECT *
FROM table
WHERE column_name ILIKE "%value%"