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How to add a primary key to a MySQL table?
...le as it is written now, which can be a little confusing when doing simple SELECT * ...
– StefanK
Apr 12 '19 at 6:45
H...
How to find duplicates in 2 columns not 1
..._title for each row.
As far as finding the existing duplicates try this:
select stone_id,
upcharge_title,
count(*)
from your_table
group by stone_id,
upcharge_title
having count(*) > 1
...
Get current AUTO_INCREMENT value for any table
...'TableName' ;
You can get exactly this information by using this query:
SELECT `AUTO_INCREMENT`
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'DatabaseName'
AND TABLE_NAME = 'TableName';
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Unknown Column In Where Clause
...om right to left. So the where clause is parsed and evaluate prior to the select clause. Because of this the aliasing of u_name to user_name has not yet occurred.
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...
Two single-column indexes vs one two-column index in MySQL?
... the statement I provided.
Additionally, MySQL can only use one index per SELECT so a covering index would be the best means of optimizing your queries.
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SQL UPDATE SET one column to be equal to a value in a related table referenced by a different column
...result set to update is before running the update (same query, just with a select):
select *
from QuestionTrackings q
inner join QuestionAnswers a
on q.AnswerID = a.AnswerID
where q.QuestionID is null -- and other conditions you might want
Particularly whether each answer id has definitely only 1...
How to find all tables that have foreign keys that reference particular table.column and have values
...
Here you go:
USE information_schema;
SELECT *
FROM
KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_NAME = 'X'
AND REFERENCED_COLUMN_NAME = 'X_id';
If you have multiple databases with similar tables/column names you may also wish to limit your query to a particul...
MySQL 'create schema' and 'create database' - Is there any difference
...asn't been allocated to any particular schema, you can do something like:
SELECT *
FROM your_table
which is equivalent to:
SELECT *
FROM dbo.your_table
Now, SQL server allows the creation of different schema, which gives you the possibility of grouping tables that share a similar purpose. That...
Find and Replace text in the entire table using a MySQL query
...his_text";
$replace = "replace_with_this_text";
$loop = mysql_query("
SELECT
concat('UPDATE ',table_schema,'.',table_name, ' SET ',column_name, '=replace(',column_name,', ''{$find}'', ''{$replace}'');') AS s
FROM
information_schema.columns
WHERE
table_schema = '{...
How do I check if an index exists on a table field in MySQL?
...
Try:
SELECT * FROM information_schema.statistics
WHERE table_schema = [DATABASE NAME]
AND table_name = [TABLE NAME] AND column_name = [COLUMN NAME]
It will tell you if there is an index of any kind on a certain column wi...