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When should I use a composite index?
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@felwithe MySQL can only use one index per each of the tables in a query (Exemptions are there. eg, Merging of indexes). Which ideally means that a table in a query, must use a single index for all where-clause, table join, group-by an...
Reading an Excel file in PHP [closed]
... you want to use the data in the excel file. If you want to import it into mysql, you could simply save it as a CSV formatted file and then use fgetcsv to parse it.
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MYSQL Truncated incorrect DOUBLE value
...ally whenever there is some Syntax issue it throws this useless exception "mysql-truncated-incorrect-double-value"
– heman123
May 10 '18 at 11:47
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MySQL LIKE IN()?
...eing sufficient to give me the correct results, using LIKE as well allowed MySQL to reduce the result set considerably before having to use the slower REGEXP criteria.
– mpen
Feb 15 '12 at 0:11
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Tactics for using PHP in a high-load site
...l you measure and compare your changes.
For example, for many years, the MySQL query cache was the solution to all of our performance problems. If your site was slow, MySQL experts suggested turning the query cache on. It turns out that if you have a high write load, the cache is actually cripplin...
Multiple columns index when using the declarative ORM extension of sqlalchemy
...f you have a dictionary for table_args like I currently do? table_args = {'mysql_engine':'InnoDB'}
– Nick Holden
Sep 1 '11 at 8:39
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Does MySQL ignore null values on unique constraints?
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Yes, MySQL allows multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);...
How do I check if a column is empty or null in MySQL?
...OR some_col = ' ' (one space inserted in the string) then it works on both MySQL and Oracle, see answer of "onedaywhen". some_col = '' doesn't work on Oracle as empty strings mean NULL there.
– Johanna
May 18 '15 at 14:07
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How do I show the schema of a table in a MySQL database?
From the MySQL console, what command displays the schema of any given table?
5 Answers
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How to delete from multiple tables in MySQL?
...h out to an EXISTS in 99% of the cases and then there is the 1% where this MySQL syntax takes the day.
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