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What's the difference between NOT EXISTS vs. NOT IN vs. LEFT JOIN WHERE IS NULL?
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Another point is that if table1 .a contains NULL the EXISTS query will not return this row but the NOT IN query will if table2 is empty. NOT IN vs. NOT EXISTS Nullable Columns: SQL Server
– Martin Smith
Jun 19 '...
Why is SELECT * considered harmful?
...work. This is especially true when someone adds new columns to underlying tables that didn't exist and weren't needed when the original consumers coded their data access.
Indexing issues. Consider a scenario where you want to tune a query to a high level of performance. If you were to use *, and ...
Set the table column width constant regardless of the amount of text in its cells?
In my table I set the width of the first cell in a column to be 100px .
However, when the text in one of the cell in this column is too long, the width of the column becomes more than 100px . How could I disable this expansion?
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Effect of NOLOCK hint in SELECT statements
...2) Yes, a select with NOLOCK will allow other queries against the effected table to complete faster than a normal select.
Why would this be?
NOLOCK typically (depending on your DB engine) means give me your data, and I don't care what state it is in, and don't bother holding it still while you re...
What are the differences between “=” and “
...expression). In fact, ?Syntax in R gives the following operator precedence table, from highest to lowest:
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‘-> ->>’ rightwards assignment
‘<- <<-’ assignment (right to left)
‘=’ assignment (right to left)
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But is this the on...
Check if all elements in a list are identical
... explanation of alternatives. Can you please double check your performance table - is it all in msec, and are the numbers in the correct cells?
– max
Oct 2 '10 at 8:26
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Saving timestamp in mysql table using php
I have a field in a MySQL table which has a timestamp data type. I am saving data into that table. But when I pass the timestamp ( 1299762201428 ) to the record, it automatically saves the value 0000-00-00 00:00:00 into that table.
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How to deal with SQL column names that look like SQL keywords?
...ause I didn't make it.
Am I allowed to do something like SELECT from FROM TableName or is there a special syntax to avoid the SQL Server being confused?
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Select top 10 records for each category
.... Can anyone help with how to do it? Section is one of the columns in the table.
14 Answers
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Set NOW() as Default Value for datetime datatype?
I have two columns in table users namely registerDate and lastVisitDate which consist of datetime data type. I would like to do the following.
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