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Is the primary key automatically indexed in MySQL?
...m/doc/refman/5.5/en/optimizing-primary-keys.html
The primary key for a table represents the column or set of columns
that you use in your most vital queries. It has an associated index,
for fast query performance
For MySQL 5.0 reference see: http://dev.mysql.com/doc/refman/5.0/en/mysql-ind...
Limiting the number of records from mysqldump?
...atabase
Of course, that would give you the first million rows from every table.
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Postgres dump of only parts of tables for a dev snapshot
...
On your larger tables you can use the COPY command to pull out subsets...
COPY (SELECT * FROM mytable WHERE ...) TO '/tmp/myfile.tsv'
COPY mytable FROM 'myfile.tsv'
https://www.postgresql.org/docs/current/static/sql-copy.html
You shoul...
How do I get SUM function in MySQL to return '0' if no values are found?
...Use COALESCE to avoid that outcome.
SELECT COALESCE(SUM(column),0)
FROM table
WHERE ...
To see it in action, please see this sql fiddle: http://www.sqlfiddle.com/#!2/d1542/3/0
More Information:
Given three tables (one with all numbers, one with all nulls, and one with a mixture):
SQL Fidd...
How to quickly edit values in table in SQL Server Management Studio?
...> "Edit Top 200 Rows" from Object Explorer, is there a quick way to open a table in Edit mode where I can just quickly modify the value of a cell?
...
Mysql order by specific ID values
...and FIELD function.
See http://lists.mysql.com/mysql/209784
SELECT * FROM table ORDER BY FIELD(ID,1,5,4,3)
It uses Field() function, Which "Returns the index (position) of str in the str1, str2, str3, ... list. Returns 0 if str is not found" according to the documentation. So actually you sort th...
How do I execute a stored procedure once for each row returned by query?
... way. I pass it user_id and it does it's thing. I want to run a query on a table and then for each user_id I find run the stored procedure once on that user_id
...
SQL Server : Columns to Rows
...nto rows:
select id, entityId,
indicatorname,
indicatorvalue
from yourtable
unpivot
(
indicatorvalue
for indicatorname in (Indicator1, Indicator2, Indicator3)
) unpiv;
Note, the datatypes of the columns you are unpivoting must be the same so you might have to convert the datatypes prior t...
sql server invalid object name - but tables are listed in SSMS tables list
.... However the SSMS intellisense does not recognize more than half of the tables which have been created.
16 Answers
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Deleting Row in SQLite in Android
...tion, but I'm new to SQLite and I can't seem to figure this out. I have 1 table that has columns KEY_ROWID , KEY_NAME , KAY_LATITUDE , and KEY_LONGITUDE . I want the user to be able to select one and delete it; Can anyone give me a direction to start in? My question is in the actual deletion ...