SQL Refresher - SQL REFRESHER Basic SQL Commands SQL...

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SQL REFRESHER Basic SQL Commands
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SQL Structured Query Language Structured English Query Language (SEQUEL or SEQL) Donald D. Chamberlin and Raymond F. Boyce at IBM Scope: Data query and update (DML) Schema creation and modification (DDL) Data access control (DCL)
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Purpose Provide an interface to a relational database such as Oracle Database Hence: SQL statements are instructions to the database SQL provides statements for a variety of tasks, including: Querying data Inserting, updating, and deleting rows in a table Creating, replacing, altering, and dropping objects Controlling access to the database and its objects Guaranteeing database consistency and integrity
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Language Elements Clauses Expressions Predicates / Conditions Queries Statements Insignificant whitespace
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Queries Most common operation in SQL DML deals with queries and data manipulation Performed with SELECT SELECT * | column_name [, column_name] FROM table_name WHERE condition AND | OR condition
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Queries - SELECT SELECT lists the fields or columns you want to retrieve, FROM tells you where you want to get your data, and WHERE restricts the rows
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SQL Refresher - SQL REFRESHER Basic SQL Commands SQL...

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