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How to declare a variable in a PostgreSQL query
... work as a variable, or even tuple of variables. It allows you to return a table of temporary values.
WITH master_user AS (
SELECT
login,
registration_date
FROM users
WHERE ...
)
SELECT *
FROM users
WHERE master_login = (SELECT login
FROM master_user)...
How do I show the schema of a table in a MySQL database?
From the MySQL console, what command displays the schema of any given table?
5 Answers
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EF Code First “Invalid column name 'Discriminator'” but no inheritance
I have a table in my database called SEntries (see below the CREATE TABLE statement). It has a primary key, a couple of foreign keys and nothing special about it. I have many tables in my database similar to that one, but for some reason, this table ended up with a "Discriminator" column on the EF P...
How to find all the tables in MySQL with specific column names in them?
...rent column names that I want to look up in the entire DB and list out all tables which have those columns. Any easy script?
...
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 ...
Printing the value of a variable in SQL Developer
...
DECLARE
CTABLE USER_OBJECTS.OBJECT_NAME%TYPE;
CCOLUMN ALL_TAB_COLS.COLUMN_NAME%TYPE;
V_ALL_COLS VARCHAR2(5000);
CURSOR CURSOR_TABLE
IS
SELECT OBJECT_NAME
FROM USER_OBJECTS
WHERE OBJECT_TYPE='TABLE'
AND OBJ...
Oracle query to fetch column names
I have a mySQL query to get columns from a table like this:
12 Answers
12
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How many database indexes is too many?
...
It depends on the operations that occur on the table.
If there's lots of SELECTs and very few changes, index all you like.... these will (potentially) speed the SELECT statements up.
If the table is heavily hit by UPDATEs, INSERTs + DELETEs ... these will be very slow w...
How to align content of a div to the bottom
...ignment issues with the items aren't fixed height, it's easier just to use tables.
Example: Can you do this HTML layout without using tables?
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Multiple Updates in MySQL
... use INSERT ... ON DUPLICATE KEY UPDATE.
Using your example:
INSERT INTO table (id,Col1,Col2) VALUES (1,1,1),(2,2,3),(3,9,3),(4,10,12)
ON DUPLICATE KEY UPDATE Col1=VALUES(Col1),Col2=VALUES(Col2);
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