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Add column to SQL Server
I need to add a column to my SQL Server table. Is it possible to do so without losing the data, I already have?
5 Answers...
How do I create a SQL table under a different schema?
...
Right-click on the tables node and choose New Table...
With the table designer open, open the properties window (view -> Properties Window).
You can change the schema that the table will be made in by choosing a schema in the properties wind...
How to create materialized views in SQL Server?
...ually I want to create a view and it should update automatically when base tables are changed. Can anyone explain with an query example..
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ROW_NUMBER() in MySQL
... kind of isn't).
I often plump for a null-self-join:
SELECT t0.col3
FROM table AS t0
LEFT JOIN table AS t1 ON t0.col1=t1.col1 AND t0.col2=t1.col2 AND t1.col3>t0.col3
WHERE t1.col1 IS NULL;
“Get the rows in the table for which no other row with matching col1,col2 has a higher col3.” (You w...
INNER JOIN ON vs WHERE clause
...It is generally considered more readable, especially when you join lots of tables.
It can also be easily replaced with an OUTER JOIN whenever a need arises.
The WHERE syntax is more relational model oriented.
A result of two tables JOINed is a cartesian product of the tables to which a filter is ...
INSERT INTO…SELECT for all MySQL columns
...The correct syntax is described in the manual. Try this:
INSERT INTO this_table_archive (col1, col2, ..., coln)
SELECT col1, col2, ..., coln
FROM this_table
WHERE entry_date < '2011-01-01 00:00:00';
If the id columns is an auto-increment column and you already have some data in both tables the...
How can I create a table with borders in Android?
I use a table layout to display data as table, but I want a table with user-defined columns and rows with borders. Suggestions?
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How can foreign key constraints be temporarily disabled using T-SQL?
... database just run this code:
-- disable all constraints
EXEC sp_MSforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"
To switch them back on, run: (the print is optional of course and it is just listing the tables)
-- enable all constraints
exec sp_MSforeachtable @command1="print '?'", @command...
Favourite performance tuning tricks [closed]
...e following...
99% of problems I have seen are caused by putting too many tables in a join. The fix for this is to do half the join (with some of the tables) and cache the results in a temporary table. Then do the rest of the query joining on that temporary table.
Query Optimisation Checklist
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What is cardinality in MySQL?
... of data values contained in a particular column (attribute) of a database table. The lower the cardinality, the more duplicated elements in a column. Thus, a column with the lowest possible cardinality would have the same value for every row. SQL databases use cardinality to help determine the opti...