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Alter MySQL table to add comments on columns
I have been checking the MySQL Documentation for ALTER TABLE and it does not seem to include a way to add or modify a comment to a column. How can I do this?
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Get size of all tables in database
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SELECT
t.NAME AS TableName,
s.Name AS SchemaName,
p.rows,
SUM(a.total_pages) * 8 AS TotalSpaceKB,
CAST(ROUND(((SUM(a.total_pages) * 8) / 1024.00), 2) AS NUMERIC(36, 2)) AS TotalSpaceMB,
SUM(a.used_pages) * 8 AS UsedSpaceK...
How do you return the column names of a table?
How would I return the column names of a table using SQL Server 2008? i.e. a table contains these columns- id, name, address, country and I want to return these as data.
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What's the best way to join on the same table twice?
This is a little complicated, but I have 2 tables. Let's say the structure is something like this:
5 Answers
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Cannot simply use PostgreSQL table name (“relation does not exist”)
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From what I've read, this error means that you're not referencing the table name correctly. One common reason is that the table is defined with a mixed-case spelling, and you're trying to query it with all lower-case.
In other words, the following fails:
CREATE TABLE "SF_Bands" ( ... );
SEL...
Maximum number of records in a MySQL database table
What is the upper limit of records for MySQL database table. I'm wondering about autoincrement field. What would happen if I add milions of records? How to handle this kind of situations?
Thx!
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T-SQL query to show table definition?
...l show me the full definition, including indexes and keys for a SQL Server table? I want a pure query - and know that SQL Studio can give this to me, but I am often on "wild" computers that have only the most bare-bones apps and I have no rights to install studio. But SQLCMD is always an option.
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Mysql error 1452 - Cannot add or update a child row: a foreign key constraint fails
... having a bit of a strange problem. I'm trying to add a foreign key to one table that references another, but it is failing for some reason. With my limited knowledge of MySQL, the only thing that could possibly be suspect is that there is a foreign key on a different table referencing the one I am ...
Best way to select random rows PostgreSQL
...erves nicely.
The query below does not need a sequential scan of the big table, only an index scan.
First, get estimates for the main query:
SELECT count(*) AS ct -- optional
, min(id) AS min_id
, max(id) AS max_id
, max(id) - min(id) AS id_span
FROM big;
The on...
Rails migration for change column
We have script/generate migration add_fieldname_to_tablename fieldname:datatype syntax for adding new columns to a model.
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