Working with Data

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The majority of SQL statements in an embedded program are devoted to reading or modifying existing data, or adding new data to a database. This chapter describes the types of data recognized by InterBase, and how to retrieve, modify, add, or delete data in a database using SQL expressions and the following statements.

SELECT statements query a database, that is, read or retrieve existing data from a database. Variations of the SELECT statement make it possible to retrieve:

• A single row, or part of a row, from a table. This operation is referred to as a singleton select.
• Multiple rows, or parts of rows, from a table using a SELECT within a DECLARE CURSOR statement.
• Related rows, or parts of rows, from two or more tables into a virtual table, or results table. This operation is referred to as a join.
• All rows, or parts of rows, from two or more tables into a virtual table. This operation is referred to as a union.

• INSERT statements write new rows of data to a table.
• UPDATE statements modify existing rows of data in a table.
• DELETE statements remove existing rows of data from a table.

To learn how to use the SELECT statement to retrieve data, see Understanding Data Retrieval with SELECT. For information about retrieving a single row with SELECT, see Selecting a Single Row. For information about retrieving multiple rows, see Selecting Multiple Rows.

For information about using INSERT to write new data to a table, see Inserting Data. To modify data with UPDATE, see Updating Data. To remove data from a table with DELETE, see Deleting Data.

Topics

• Supported Data Types
• Understanding SQL Expressions
• Understanding Data Retrieval with SELECT
• Selecting a Single Row
• Selecting Multiple Rows
• Selecting Multiple Rows in DSQL
• Joining Tables
• Using Subqueries
• Inserting Data
• Updating Data
• Deleting Data