Learning bLog

I tried one query (originally asked at JR) on MySQL which export the table data into a file, with a comma delimited field. The query is straight forward and replace the null column value by "\N" character, but when I want to replace that "\N" value by some other character like "0" or simple empty field like " ", its gets little tricky. Here is the base query SELECT Id, name, age FROM student INTO OUTFILE 'c:/result.txt' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n'; And it outputs like, 1, "sagar", 23 2, "anant", 24 Now suppose some 'name' fields are null, then it outputs like 1, "sagar", 23 2, \N, 24 Now to obtain my desired results, which replace this null (\N) values by empty string like, "", I tried out two solutions --1. Using CASE statement SELECT Id, CASE WHEN name IS NULL THEN '' ELSE name END AS NewName, age FROM s...

I'm weak in databases and consult Google every time if I'm new to the concept OR baffled somewhere. Some days back I got simple requirement which is nothing but to drop the PK constraint from a table, Initially I thought it was easy to do but got stuck and finally came up with solution.This is what straight forward thing I did -- Problem: Remove the PK constraint from the table 'test', -- Solution: -- 1. Get the table constraint using following query SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = 'test'; -- 2. It returns a column CONSTRAINT_NAME with the list of constraint, like, PK, FK, etc --|CONSTRAINT_NAME| ------------------- --|PK_test | -- 3. The PK constraint name generally starts with "PK_table_name[_xxx]" -- 4. Remove it using following query ALTER TABLE test DROP CONSTRAINT PK_test; -- 5. You just drop the PK constraint from table 'test', hurray !!! :) Hope this hel...