oracle sql tutorial

Oracle SQL Tutorial

Oracle SQL is the SQL language for the relational database Oracle. SQL is the abbreviation of Structured Query Language, which is used to perform operations such as additions, deletions, modifications, and queries on relational databases. Oracle SQL includes a large number of SQL statements that can be used to retrieve data from tables, insert and update data, and delete data. In this article, we will cover the basics and advanced features of Oracle SQL.

1. Introduction to Oracle SQL
Oracle SQL is the query language of the Oracle database system. Oracle SQL provides a simple way to query, update, and manage data in Oracle Database. The Oracle SQL language is an extended version of the ANSI/ISO SQL standard.

2. Oracle SQL basic statements

1. SELECT statement
   The SELECT statement is the basic statement used to retrieve data in the database in Oracle SQL. The following is the syntax of the SELECT statement:
   SELECT column1, column2, … column_n FROM table_name;

Among them, column1, column2, … column_n is the name of the column to be retrieved, and table_name is the name to be retrieved The name of the data table.

2. INSERT INTO statement
   The INSERT INTO statement is used to insert new data into the Oracle database. The following is the syntax of the INSERT INTO statement:
   INSERT INTO table_name (column1, column2, … column_n) VALUES (value1, value2, … value_n);

where table_name is the table into which data is to be inserted. The name of column1, column2, … column_n is the name of the column into which data is to be inserted, and value1, value2, … value_n is the value to be inserted.

3. UPDATE Statement
   The UPDATE statement is used to update existing data in an Oracle database. The following is the syntax of the UPDATE statement:
   UPDATE table_name SET column1 = value1, column2 = value2, … column_n = value_n WHERE condition;

Where, table_name is the name of the data table to be updated, column1 , column2, … column_n are the names of the columns to be updated, value1, value2, … value_n are the values ​​to be updated, and condition is the update condition.

4. DELETE Statement
   The DELETE statement is used to delete data from an Oracle database. The following is the syntax of the DELETE statement:
   DELETE FROM table_name WHERE condition;

where table_name is the name of the table to delete data, and condition is the deletion condition.

3. Oracle SQL advanced features

1. JOIN
   JOIN is a method to join two or more tables in Oracle SQL. The following is the syntax of the JOIN statement:
   SELECT * FROM table1 JOIN table2 ON table1.column_name = table2.column_name;

Where, table1 and table2 are the names of the tables to be connected.

2. Subquery
   A subquery is a method used in Oracle SQL to use the results of one query as a condition for another query. The following is the syntax of the subquery:
   SELECT column_names FROM table_name WHERE column_name OPERATOR (SELECT column_name FROM table_name WHERE condition);

Where column_names is the name of the column to be retrieved, table_name is the name of the column to be retrieved The name of the data table, column_name is the name of the column to be retrieved.

3. Grouping and Aggregation
   Grouping and aggregation are methods used in Oracle SQL to perform complex operations on data. The following is the syntax for grouping and summarizing:
   SELECT column_name1, SUM(column_name2) FROM table_name GROUP BY column_name1;

where column_name1 is the name of the column to be grouped, and column_name2 is the column to be summarized The name.

4. Stored Procedures
   Stored procedures are a way to perform complex tasks in Oracle SQL. The following is the syntax of a stored procedure:
   CREATE PROCEDURE procedure_name IS BEGIN statement1; statement2; … statement_n; END;

where procedure_name is the name of the stored procedure.

4. Summary
Oracle SQL is a powerful query language used in the Oracle database system. It has extensive functionality and advanced features, including JOINs, subqueries, grouping and aggregation, and stored procedures. Understanding these capabilities will enable you to work with data in Oracle Database more efficiently.

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