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How do I check if a column is empty or null in MySQL?
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This will select all rows where some_col is NULL or '' (empty string)
SELECT * FROM table WHERE some_col IS NULL OR some_col = '';
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SQL: How to properly check if a record exists
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It's better to use either of the following:
-- Method 1.
SELECT 1
FROM table_name
WHERE unique_key = value;
-- Method 2.
SELECT COUNT(1)
FROM table_name
WHERE unique_key = value;
The first alternative should give you no result or one result, the second count should be zero or on...
Vim search and replace selected text
Let's say we have a text, and I enter visual mode and select some text. How do I quickly do a search for the highlighted text and replace it with something else?
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MySQL select where column is not empty
In MySQL, can I select columns only where something exists?
13 Answers
13
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Is there an onSelect event or equivalent for HTML ?
I have an input form that lets me select from multiple options, and do something when the user changes the selection. Eg,
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Selecting data from two different servers in SQL Server
How can I select data in the same query from two different databases that are on two different servers in SQL Server?
15 An...
SQL Server loop - how do I loop through a set of records
how do I loop through a set of records from a select?
8 Answers
8
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Find rows that have the same value on a column in MySQL
...sses and how many times they're used, with the most used addresses first.
SELECT email,
count(*) AS c
FROM TABLE
GROUP BY email
HAVING c > 1
ORDER BY c DESC
If you want the full rows:
select * from table where email in (
select email from table
group by email having count(*) &g...
Counting null and non-null values in a single query
...le and SQL Server (you might be able to get it to work on another RDBMS):
select sum(case when a is null then 1 else 0 end) count_nulls
, count(a) count_not_nulls
from us;
Or:
select count(*) - count(a), count(a) from us;
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How to remove an iOS app from the App Store
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What you need to do is this.
Go to “Manage Your Applications” and select the app.
Click “Rights and Pricing” (blue button at the top right.
Below the availability date and price tier section, you should see a grid of checkboxes for the various countries your app is available in. Click t...