3.1

SQL Conditional Statements

• IN clause

  • Used to determine if a value matches one of several values.

  • Example: WHERE column IN (value1, value2, value3).

• BETWEEN clause

  • An alternative way to determine if a value lies between two other values.

  • Syntax: value BETWEEN minvalue AND maxvalue inclusive.

SQL Pattern Matching

• LIKE operator

  • Characterizes any number of characters.

  • Example: LIKE 'cat%' matches any string that starts with "cat".

  • Matches one character: LIKE 'c_t' matches "cat", "cot", etc.

• Case Sensitivity

  • By default, LIKE performs case-insensitive pattern matching.

  • If followed by the BINARY keyword, it performs case-sensitive matching.

SQL Queries: Examples

• Example Queries

  • SELECT * FROM CountryLanguage WHERE CountryCode LIKE 'A_W';

    • This retrieves entries where CountryCode matches the pattern.

  • SELECT * FROM CountryLanguage WHERE Language LIKE 'A%n';

    • This retrieves languages starting with "A".

  • SELECT DISTINCT Language FROM CountryLanguage WHERE ISOfficial = 'F';

    • This returns unique languages where ISOfficial is False.

DISTINCT Keyword

• DISTINCT clause

  • Used with SELECT to return only unique or distinct values.

  • Example in usage: SELECT DISTINCT Language FROM CountryLanguage;

  • This command retrieves unique languages from the CountryLanguage table.

SQL Ordering

• ORDER BY clause

  • Utilized to sort rows in a specified order.

  • The DESC keyword indicates descending order.