Chapter 2. Retrieving Data (SELECT)
Terms You Need to Understand
✓ The SELECT statement
✓ The FROM clause
✓ Query
✓ Column and column list
✓ Schema
✓ Expression
✓ Alias
✓ DISTINCT versus ALL
✓ NULL
Concepts You Need to Master
✓ What a query is
✓ What an expression is
✓ The difference between a column and an expression
✓ Simple queries
✓ The DUAL table
✓ The effect of NULL values on the result of expressions
✓ The DISTINCT clause
✓ Repeating groups
This chapter jumps straight into the basic syntax of data retrieval using the Oracle SQL SELECT
statement, additionally briefly introducing some specifics.
What Is a Query?
A query is a statement interrogating the database and returning information. Most often tables are interrogated and rows from those tables are returned. ...
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