Essential SQL Commands

You must commit your current transaction to make permanent all of its changes to the database. The arguments for the ALTER VIEW command are listed in Table 4-11. The arguments for the ALTER USER command are listed in Table 4-10. You can change your user password in the database if you meet one of the following conditions.

Basic SQL commands

The syntax for the COLUMN CONSTRAINT clause is displayed in Figure 4-11. After disabling the trigger, you can subsequently enable it with the following statement. When the trigger is disabled, Oracle Database Lite does not fire the trigger when an UPDATE statement causes the part’s inventory to fall below its reorder point. The syntax diagrams in this document use a variation of Backus-Nauer Form (BNF), a convention used to show syntax in many programming languages. Emphasis and symbols have the following meaning in this version of BNF syntax. Oracle Database Lite uses several different types of SQL commands.

Essential SQL Commands

It is used to specify the columns on which the two tables will be joined. Usually, those are the columns that store the same data in both tables. In other words, we join the tables on the primary and foreign keys. A primary key is a column (or columns) that uniquely defines each row in the table. A foreign key is a column in the second table that refers to the first table. In our example, the column id from the table employees is its primary key.

Understanding the sequence in which SQL commands are executed is crucial. Begin by creating a database, followed by tables within that database. Once your tables are set up, you can manipulate data by inserting, updating, or deleting. Finally, use the SELECT command to query and retrieve the data you basis sql need. This tutorial provides an overview of the most commonly used SQL commands to create, alter, and manipulate tables and data in databases. SQL commands can be used to search the database and to do other functions like creating tables, adding data to tables, modifying data, and dropping tables.


The CREATE SCHEMA statement can include the CREATE TABLE, CREATE VIEW, and GRANT statements. To issue a CREATE SCHEMA statement, you must be logged into the database as SYSTEM or as a user with DBA/DDL or ADMIN privileges. To create a procedure in your own schema, you must be connected to the database as SYSTEM or you must have DBA/DDL privileges. The following statement creates a Java resource schema object named APPTEXT from a binary file.

  • Now that we have two tables joined, we are free to select any column from both tables.
  • This training will help you understand MySQL in depth and help you achieve mastery over the subject.
  • An active savepoint is one marked since the last commit or rollback.
  • If an ORDER BY clause follows ROWNUM in the same subquery, the rows are reordered by the ORDER BY clause.
  • The number of aliases must match the number of expressions selected by the query.

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