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MySQL - why not index every field?
...k about index updates were one update trigger all indexes update this is a select all unordered equivalent in time
from this I conclude that you have in this scenario that if you will loose this time is preferable to lose it in a select nor an update because if you will select a field that is not i...
String concatenation in MySQL
...most DBMSs use of + or || for concatenation. It uses the CONCAT function:
SELECT CONCAT(first_name, " ", last_name) AS Name FROM test.student
As @eggyal pointed out in comments, you can enable string concatenation with the || operator in MySQL by setting the PIPES_AS_CONCAT SQL mode.
...
How to escape single quotes in MySQL
...
Put quite simply:
SELECT 'This is Ashok''s Pen.';
So inside the string, replace each single quote with two of them.
Or:
SELECT 'This is Ashok\'s Pen.'
Escape it =)
...
Types in MySQL: BigInt(20) vs Int(20)
...E TABLE foo ( bar INT(20) ZEROFILL );
INSERT INTO foo (bar) VALUES (1234);
SELECT bar from foo;
+----------------------+
| bar |
+----------------------+
| 00000000000000001234 |
+----------------------+
It's a common source of confusion for MySQL users to see INT(20) and assume ...
How can I see the specific value of the sql_mode?
...mode. If you set it, then that query will show you the details:
mysql> SELECT @@sql_mode;
+------------+
| @@sql_mode |
+------------+
| |
+------------+
1 row in set (0.00 sec)
mysql> set sql_mode=ORACLE;
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT @@sql_mode;
+-------...
MySQL remove all whitespaces from the entire column
...
Working Query:
SELECT replace(col_name , ' ','') FROM table_name;
While this doesn't :
SELECT trim(col_name) FROM table_name;
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Unknown column in 'field list' error on MySQL Update query
..._user_profile.fellow = 'y'
WHERE
master_user_profile.user_id IN (
SELECT tran_user_branch.user_id
FROM tran_user_branch WHERE tran_user_branch.branch_id = 17);
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MySQL check if a table exists without throwing an exception
...
If you're using MySQL 5.0 and later, you could try:
SELECT COUNT(*)
FROM information_schema.tables
WHERE table_schema = '[database name]'
AND table_name = '[table name]';
Any results indicate the table exists.
From: http://www.electrictoolbox.com/check-if-mysql-table-exis...
For loop example in MySQL
...+1;
end while;
commit;
end #
delimiter ;
call load_foo_test_data();
select * from foo order by id;
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Convert text into number in MySQL query
...
This should work:
SELECT field,CONVERT(SUBSTRING_INDEX(field,'-',-1),UNSIGNED INTEGER) AS num
FROM table
ORDER BY num;
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