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How to count occurrences of a column value efficiently in SQL?
...
This should work:
SELECT age, count(age)
FROM Students
GROUP by age
If you need the id as well you could include the above as a sub query like so:
SELECT S.id, S.age, C.cnt
FROM Students S
INNER JOIN (SELECT age, count(age) a...
what is the difference between GROUP BY and ORDER BY in sql
... SUM, COUNT, AVG, etc).
TABLE:
ID NAME
1 Peter
2 John
3 Greg
4 Peter
SELECT *
FROM TABLE
ORDER BY NAME
=
3 Greg
2 John
1 Peter
4 Peter
SELECT Count(ID), NAME
FROM TABLE
GROUP BY NAME
=
1 Greg
1 John
2 Peter
SELECT NAME
FROM TABLE
GROUP BY NAME
HAVING Count(ID) > 1
=
Peter
...
Get table names using SELECT statement in MySQL
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To get the name of all tables use:
SELECT table_name FROM information_schema.tables;
To get the name of the tables from a specific database use:
SELECT table_name FROM information_schema.tables
WHERE table_schema = 'your_database_name';
Now, to answer the...
PostgreSQL function for last inserted ID
...e:
INSERT INTO persons (lastname,firstname) VALUES ('Smith', 'John');
SELECT currval('persons_id_seq');
The name of the sequence must be known, it's really arbitrary; in this example we assume that the table persons has an id column created with the SERIAL pseudo-type. To avoid relying on thi...
How to import a jar in Eclipse
...o this folder all the jar files you need.
Refresh your project in eclipse.
Select all the jar files, then right click on one of them and select Build Path -> Add to Build Path
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How to change the blue highlight color of a UITableViewCell?
I'm wondering how to change the blue highlight/selection color of a UITableViewCell , any ideas?
11 Answers
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SQL Server - SELECT FROM stored procedure
...le result sets, each with its own schema. It's not suitable for using in a SELECT statement.
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mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to
I am trying to select data from a MySQL table, but I get one of the following error messages:
31 Answers
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How to auto-indent code in the Atom editor?
...auto-indent your code in the Atom editor? In other editors you can usually select some code and auto-indent it.
11 Answers...
Locate current file in IntelliJ
...ecause you followed a reference to java.io.File.
The keymap defines it as Select current file or symbol in any view.
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