Return a value if no rows are found SQL
What actually happens when you run a SQL query that doesn’t return any rows? For example, think of a WHERE clause with the condition 1=2, which can never be fulfilled and therefore rows can...
Category: Education
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SQL Developer Memory Settings
Your SQL Developer is behaving slowly when starting and executing queries? Then I have the right tips for you here. Two blog articles already deal with the optimization of SQL Developer. On the one...
SQL Developer Slow
Is your SQL developer slow? Then here are a few tips and tricks to make it a little faster. Note that you use the Always optimize SQL Developerand you should also download the latest...
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Differences between NVL, NVL2 and COALESCE
NVL and NVL2 are Oracle specific and where introduced before the ANSI-92 standard (which includes COALESCE) was created. NVL and COALESCE are nearly identical, even there are some differenced I would like to point...
Flashback Query – The SQL statement in distress
Accidentally, important data was deleted. Of course not in a test system but during operation. The pulse and blood pressure rises. But do not worry – it is not always necessary to back up...
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SQL Formula (Math Functions)
If you want to calculate a value with a function which is stored in the table (row or column) you can use the follwing code to execute the math formula. Replace placeholders with the...
Autonomous Transactions
PL/SQL normally treads the whole modification as a single transaction. If you want to have some part of the code as seperate transaction, you can use the functionallity of autonomous transactions. The statement PRAGMA...
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SQL Aggregation
Aggregation Cube If you have dimensions, you can use the cube function. Imagine you have the dimensions time, state and product. When you use the cube function, you can get an insight of these...
APEX Office Print (AOP) – Problems Excel Text Wrap, Line Break
Problem An Excel template was created (with the variables according to AOP) including line wrapping (text wrap, line break). During the subsequent document creation, however, the line break is not taken into account (not...
Write protection of tables
Write protection can be applied to tables. This prevents DDL (Data Definition Language) and DML (Data Manipulation Language) changes during maintenance mode. The statement: ALTER TABLE tablename READ ONLY; — nur mehr lesbar ALTER...
