MYSQL DELETE rows in query with substr - mysql

I would like to remove rows table1.name from table where table1.name starts with 'product-'
mysql_request("DELETE FROM table1 WHERE substr(name, 0, 8) = 'product-'");
It's very ridiculous but this query doesn't work at all. Any ideas how to make it?


the key is start with 'product'. Try:
DELETE FROM table1 WHERE name like 'product-%'


Try this:
DELETE FROM table1 WHERE name like 'product-%';
or this (regular expressions syntax):
DELETE FROM table1 WHERE name REGEXP '^product-';


Hm - Looks good. Should work (provided you switched to the correct database). Do you have an error message?
Another possible approach would be:
DELETE FROM table1 WHERE name like 'product-%'

Related

Count(1) and the Like statement Best use/Performance

Is there a better way of doing the below sql query I am not sure if the Like statement is the best option as the location column only contains exact matches.
INSERT INTO test_reports (Table_Name, Total_Count)
SELECT "table1", COUNT(1)
FROM table1
WHERE location LIKE 'birmingham'

There's no wildcards in your search string. Without wildcards, like is exactly the same as =.

Renaming Columns in an SQL SELECT Statement

I would like to rename the columns in the results of a SELECT expression. Of course, the following doesn't work:
SELECT * AS foobar_* FROM `foobar`
As I'm new to SQL, I think I'm just missing a concept, tool, or keyword that would lead to the answer. A hint in the right direction would be appreciated. Thanks!
UPDATE
I'm looking for a generic way to do this, and MySQL-specific techniques are absolutely fine.
In short, I'm writing a tool that "exports" the results of MySQL queries to Google Spreadsheets (via the Google Data API). Some queries are joins, so to make columns unique I wanted to prefix all column names with their respective table names.

You can alias the column names one by one, like so
SELECT col1 as `MyNameForCol1`, col2 as `MyNameForCol2`
FROM `foobar`
Edit You can access INFORMATION_SCHEMA.COLUMNS directly to mangle a new alias like so. However, how you fit this into a query is beyond my MySql skills :(
select CONCAT('Foobar_', COLUMN_NAME)
from INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME = 'Foobar'

you have to rename each column
SELECT col1 as MyCol1,
col2 as MyCol2,
.......
FROM `foobar`

select column1 as xyz,
column2 as pqr,
.....
from TableName;

MySQL Finding data using IN and LIKE Wildcard

How would I go about doing something like:
SELECT * FROM mytable
WHERE people IN ('Jack', '%Bob%')
Finding all fields that either equal 'Jack' or contain 'Bob'? I don't think my example is the proper syntax because it's not pulling up any records.

Simply :
SELECT * FROM mytable WHERE people='Jack' OR PEOPLE LIKE '%Bob%'

Use '%' with column names in MYSQL select statement?

I have a query that looks at partial matches within two mysql tables to make a join:
SELECT table1.column, table2.column FROM table1, table2 WHERE table1.val LIKE table2.val
This works fine as a join, but... some of the values in table2 are actually substrings of the values in table one—specifically they're urls. So, table1.val might equal http://google.com while table2.val = google.com.
How do I use the '%' operator around the table2 val to make this comparison.
Thanks in advance!

Like this:
... WHERE table1.val LIKE CONCAT('%', table2.val, '%')
Note that this will not perform as well as table1.val = table2.val, as it must now search all rows in table2.

Q: How do I use the '%' operator around the table2 val to make this
comparison.
A: You don't :)
You can specify a column by name (e.g. "mycolumn"), by fully qualified name (e.g. "mytable.myname") or by ordinal (e.g. "1").

MySQL Like multiple values

I have this MySQL query.
I have database fields with this contents
sports,shopping,pool,pc,games
shopping,pool,pc,games
sports,pub,swimming, pool, pc, games
Why does this like query does not work?
I need the fields with either sports or pub or both?
SELECT * FROM table WHERE interests LIKE ('%sports%', '%pub%')

Faster way of doing this:
WHERE interests LIKE '%sports%' OR interests LIKE '%pub%'
is this:
WHERE interests REGEXP 'sports|pub'
Found this solution here: http://forums.mysql.com/read.php?10,392332,392950#msg-392950
More about REGEXP here: http://www.tutorialspoint.com/mysql/mysql-regexps.htm

The (a,b,c) list only works with in. For like, you have to use or:
WHERE interests LIKE '%sports%' OR interests LIKE '%pub%'

Why not you try REGEXP. Try it like this:
SELECT * FROM table WHERE interests REGEXP 'sports|pub'

You can also use REGEXP's synonym RLIKE as well.
For example:
SELECT *
FROM TABLE_NAME
WHERE COLNAME RLIKE 'REGEX1|REGEX2|REGEX3'

Don't forget to use parenthesis if you use this function after an AND parameter
Like this:
WHERE id=123 and(interests LIKE '%sports%' OR interests LIKE '%pub%')

Or if you need to match only the beginning of words:
WHERE interests LIKE 'sports%' OR interests LIKE 'pub%'
you can use the regexp caret matches:
WHERE interests REGEXP '^sports|^pub'
https://www.regular-expressions.info/anchors.html

Your query should be SELECT * FROM `table` WHERE find_in_set(interests, "sports,pub")>0
What I understand is that you store the interests in one field of your table, which is a misconception. You should definitively have an "interest" table.

Like #Alexis Dufrenoy proposed, the query could be:
SELECT * FROM `table` WHERE find_in_set('sports', interests)>0 OR find_in_set('pub', interests)>0
More information in the manual.

More work examples:
SELECT COUNT(email) as count FROM table1 t1
JOIN (
SELECT company_domains as emailext FROM table2 WHERE company = 'DELL'
) t2
ON t1.email LIKE CONCAT('%', emailext) WHERE t1.event='PC Global Conference';
Task was count participants at an event(s) with filter if email extension equal to multiple company domains.