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Adding Oracle db cheatsheet
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@@ -81,67 +81,67 @@ OTHER FUNCTIONS
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# Sort Rows
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# Sort Rows
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Retrieve rows from a table sorted in ascending or descending order based on a specified column.
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Retrieve rows from a table sorted in ascending or descending order based on a specified column.
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SELECT * FROM table_name ORDER BY column1 [ASC|DESC];
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SELECT * FROM table_name ORDER BY column1 [ASC|DESC];
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# Count Rows
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# Count Rows
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Calculate the total number of rows in a table.
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Calculate the total number of rows in a table.
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SELECT COUNT(*) FROM table_name;
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SELECT COUNT(*) FROM table_name;
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# Limit Rows
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# Limit Rows
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Restrict the number of rows retrieved from a table.
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Restrict the number of rows retrieved from a table.
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SELECT * FROM table_name WHERE ROWNUM <= n;
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SELECT * FROM table_name WHERE ROWNUM <= n;
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# Join Tables
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# Join Tables
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Combine rows from two or more tables based on a related column.
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Combine rows from two or more tables based on a related column.
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SELECT * FROM table1 JOIN table2 ON table1.column = table2.column;
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SELECT * FROM table1 JOIN table2 ON table1.column = table2.column;
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# Group By
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# Group By
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Group rows based on the values in a specified column and perform an aggregate function.
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Group rows based on the values in a specified column and perform an aggregate function.
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SELECT column, COUNT(*) FROM table_name GROUP BY column;
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SELECT column, COUNT(*) FROM table_name GROUP BY column;
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# Aggregate Functions
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# Aggregate Functions
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Perform aggregate calculations on a column, such as average, sum, minimum, and maximum.
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Perform aggregate calculations on a column, such as average, sum, minimum, and maximum.
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SELECT AVG(column), SUM(column), MIN(column), MAX(column) FROM table_name;
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SELECT AVG(column), SUM(column), MIN(column), MAX(column) FROM table_name;
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# Subquery
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# Subquery
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Use the result of a subquery to filter data in the main query.
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Use the result of a subquery to filter data in the main query.
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SELECT column1 FROM table_name WHERE column2 = (SELECT column2 FROM another_table WHERE condition);
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SELECT column1 FROM table_name WHERE column2 = (SELECT column2 FROM another_table WHERE condition);
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# Index
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# Index
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Create an index on a column to improve query performance.
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Create an index on a column to improve query performance.
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CREATE INDEX index_name ON table_name(column1);
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CREATE INDEX index_name ON table_name(column1);
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# Drop Index
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# Drop Index
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Remove an existing index from a table.
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Remove an existing index from a table.
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DROP INDEX index_name;
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DROP INDEX index_name;
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# Constraints
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# Constraints
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Enforce data integrity by adding a primary key constraint to a table.
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Enforce data integrity by adding a primary key constraint to a table.
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ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column1);
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ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column1);
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# Sequence
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# Sequence
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Create a sequence that generates unique values for a column.
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Create a sequence that generates unique values for a column.
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CREATE SEQUENCE sequence_name START WITH 1 INCREMENT BY 1;
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CREATE SEQUENCE sequence_name START WITH 1 INCREMENT BY 1;
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# View
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# View
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Create a virtual table based on the result of a SELECT query.
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Create a virtual table based on the result of a SELECT query.
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CREATE VIEW view_name AS SELECT column1, column2 FROM table_name WHERE condition;
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CREATE VIEW view_name AS SELECT column1, column2 FROM table_name WHERE condition;
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# Stored Procedure
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# Stored Procedure
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Define and store a reusable set of SQL statements in the database.
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Define and store a reusable set of SQL statements in the database.
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CREATE OR REPLACE PROCEDURE procedure_name (parameter1 datatype, parameter2 datatype, ...) AS
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CREATE OR REPLACE PROCEDURE procedure_name (parameter1 datatype, parameter2 datatype, ...) AS
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BEGIN
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BEGIN
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@@ -150,7 +150,7 @@ END;
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/
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/
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# Trigger
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# Trigger
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Associate a set of actions with a specific table event, such as before inserting a new row.
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Associate a set of actions with a specific table event, such as before inserting a new row.
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CREATE OR REPLACE TRIGGER trigger_name
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CREATE OR REPLACE TRIGGER trigger_name
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BEFORE INSERT ON table_name
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BEFORE INSERT ON table_name
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@@ -161,7 +161,7 @@ END;
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/
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/
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# Partitioning
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# Partitioning
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Divide a large table into smaller, more manageable pieces for improved performance and maintenance.
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Divide a large table into smaller, more manageable pieces for improved performance and maintenance.
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CREATE TABLE table_name
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CREATE TABLE table_name
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PARTITION BY RANGE (column_name)
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PARTITION BY RANGE (column_name)
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