SQL Readable Outputs - Oracle SQL Fundamentals
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The document discusses the use of substitution variables in Oracle's isql*plus for managing SQL statements, including temporary storage of values and user prompting. It covers various types of substitution, how to define and use variables, and introduces the merge statement for updating and inserting records in data warehousing applications. Readers are encouraged to provide feedback on their experience with the content.
SQL Readable Outputs - Oracle SQL Fundamentals
- 1. SQL Fundamentals Oracle 11g M U H A M M A D WA H E E D O R AC L E DATA BA S E D E V E LO P E R E M A I L : m .wa h e e d 3 6 6 8 @ g m a i l . co m Lecture#9 Readable Outputs with iSQL*Plus
- 3. Substitution Variables(cont’d) Use iSQL*Plus substitution variables to: • Store values temporarily - Single ampersand( & ) - Double ampersand( && ) - DEFINE command •Pass variable values between SQL statements 3
- 4. Substitution Variables(cont’d) Use of & substitution variable: • Use a variable with pre-fixed ampersand to prompt the user for a value 4
- 5. Substitution Variables(cont’d) Use of character and date substitution variables: • Use single quotes with character and date values 5
- 6. Substitution Variables(cont’d) Use substitution variables to supplement the following : •Entire SELECT statements •Table names •Column expressions •WHERE conditions •ORDER BY clauses 6
- 7. Substitution Variables(cont’d) Use substitution variables to supplement the following : •Example: 7
- 8. Substitution Variables(cont’d) Use of DEFINE substitution variable: • Creates a user variable with the CHAR data type DEFINE variable = value (if value includes spaces than use single quotes to enclose the value) • A defined variable is available for the session 8
- 9. Substitution Variables(cont’d) Use of DEFINE and UNDEFINE commands: • A variable remains defined until you either - Use the UNDEFINE command to clear it - Exit iSQL*Plus •You can verify changes with DEFINE command 9
- 10. Substitution Variables(cont’d) Use of && with substitution variables: • If you want to reuse a variable value without prompting the user each time 10
- 11. MERGE Statement •It performs UPDATE if record exists and INSERT if record not found. •Mostly used in data warehousing applications. •Syntax: MERGE INTO <receiver_table_name> <receiver_table_alias> USING <sender_table_name> <table_alias> ON (<receiver_table_alias>.<column_name>= <sender_table_alias>.<column_name>) WHEN MATCHED THEN UPDATE SET <receiver_table_alias>.<column_name> = <sender_table_name>.<column_name> WHEN NOT MATCHED THEN INSERT VALUES(<sender_table_name>.<column_name> ,…..); 11
- 12. MERGE Statement •Syntax can be simply described as: 12
- 14. Feedback/Suggestions? Give your feedback at: [email protected] The feedback I get is that my books are honest. - Laurie Halse Anderson