Author: admin
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LOWER
Description: Converts all characters in a string to lowercase.Purpose: Standardizing data for comparisons.Syntax: LOWER(string)Parameters: Takes one string parameter.Returns: The string converted to lowercase.Example: LOWER(‘WORLD’) returns ‘world’.Notes: Affects all characters in the string.Use Case: Ensuring consistency in email addresses.
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UPPER
Description: Converts all characters in a string to uppercase.Purpose: Standardizing data for comparisons.Syntax: UPPER(string)Parameters: Takes one string parameter.Returns: The string converted to uppercase.Example: UPPER(‘hello’) returns ‘HELLO’.Notes: Affects all characters in the string.Use Case: Ensuring consistent case in user inputs.
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CASE Statements for Conditional Comparisons
Oracle SQL provides the CASE statement as a powerful tool for performing conditional logic in queries. This allows users to conduct multiple comparisons and derive new values based on specified conditions. For example:
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NULL Comparisons
In SQL, comparisons involving NULL values yield NULL results rather than TRUE or FALSE. This behavior can lead to confusion if not properly understood. For instance: This query will not return any records, as comparing any value with NULL does not yield TRUE. To check for NULL values effectively, you must use the IS NULL…
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Comparing Dates
Date comparisons in Oracle SQL can be performed using standard comparison operators, as dates are internally treated as numerical values. This characteristic enables users to compare dates directly using operators like >, <, >=, and <=. For example: This query retrieves all orders placed after January 1, 2023. Proper handling of date formats is crucial;…