Oracle 1Z0-071, SQL Constraints

Unique Constraints Requires data in the column to be unique, multiple nulls are allowed. When used in conjunction with NOT NULL, it is effectively identical to a PRIMARY KEY. Cannot be applied to UNIQUE constraint on a column of TIMESTAMP WITH TIME ZONE , CLOB or BLOB datatype. Primary Key May be applied to more…

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Oracle 1Z0-071, Subqueries

What is subquery in SQL? A subquery is simply a SQL query nested inside a larger query. You may also hear or see subqueries referred to as inner queries or inner selects, and the outer query also referred to as the parent, outer query or outer select. How the SQL Engine works Be aware that…

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Oracle 1Z0-071, Character Data Types

Objective: Using DDL Statements to Create and Manage Tables, Describe data types that are available for columns. Char Fixed length Stored 1 character as 1 byte NChar Fixed Length Stores 1 character as 2 bytes UTF-16 encoding Typical outside of America In the case of NChar or Char, if you designate a column as 10…

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