Commands

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BrandonDusch
Published Aug 1, 2021Updated Jun 25, 2022
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SQL operates through declarative statements featuring commands.

Here’s an appendix of commonly used commands.

Commands

ALTER TABLE
Adds, deletes, modifies or changes the data type of a column in a table.
AS
Renames a column or table with an alias for display, does not permanently change table/column names in the database.
CASE
Returns different output based on the conditions of each statement.
CREATE INDEX
Creates an index on existing columns in a table. Indexes cannot be seen by the user of a database; they just help speed up queries.
CREATE TABLE
Creates a new table within a database.
CREATE VIEW
Creates a virtual table based on a saved query.
CROSS JOIN
Returns a table with all possible combinations of every row from the first table and every row from the second table.
DELETE
Removes existing row(s) from a table. If a WHERE statement is excluded, all rows in the table will be deleted.
DROP TABLE
Deletes an existing table in a database.
FULL OUTER JOIN
Combines rows from different tables even if the JOIN condition is not met.
GROUP BY
Groups a result set based on an aggregate function (COUNT(), MIN(), MAX(), SUM(), AVG()). It lists the number in each group.
HAVING
A conditional statement similar to WHERE but used with aggregate functions (COUNT(), MIN(), MAX(), SUM(), AVG()).
INNER JOIN
Returns all rows that have matching values in both tables and omits non-matching rows.
INSERT INTO
Creates and places new rows into a table.
LEFT JOIN
Combines rows from two or more tables based on a related column, returning all records from the left table and matching records from the right table.
LIMIT
Specifies, or limits, the maximum number of rows the result set will have.
ORDER BY
Sorts the result set by a particular column either alphabetically or numerically.
PIVOT
Transforms rows of a table into columns.
REPLACE()
Replace all matching string parts with a specified new substring.
RIGHT JOIN
Combines matching rows with rows from the right-side table.
ROLLBACK
Undoes any work performed in the current transaction. It can also be used to undo work performed by in-doubt transactions.
ROUND()
Rounds a value to the nearest integer or to a specific number of decimals.
SELECT
Every SQL query will begin with the SELECT command to fetch data from one or more tables.
SELECT DISTINCT
Returns unique values in the specified column(s).
SELECT TOP
Returns a specified number of rows from the top of the result.
TRIM
Removes leading and trailing spaces or specified characters from a string.
TRUNCATE
Deletes all rows from a table while retaining the table structure.
UNION
Combines the results of two or more SELECT queries.
UPDATE
Edits row(s) in a table.
WHERE
Filters records (rows) that match a certain condition.
WITH
Stores the result of a query in a temporary table using an alias.

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