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What is the best way to convert an int or null to boolean value in an SQL query, such that:
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You cannot cast an integer to boolean in java. int is primitive type which has value within the range -2,147,483,648 to 2,147,483,647 whereas boolean has either true or false. So casting a number to boolean (true or false) doesn't makes sense and is not allowed in java.
You can use CAST() to convert any integer or floating-point type to BOOLEAN : a value of 0 represents false , and any non-zero value is converted to true . You can cast DECIMAL values to BOOLEAN , with the same treatment of zero and non-zero values as the other numeric types. You cannot cast a BOOLEAN to a DECIMAL .
Boolean Data Type: Literals true , false and unknown The difference between the literals null and unknown is that unknown is of type Boolean while null can take any type. Putting a not null constraint on a column of the SQL type Boolean makes it a classical two-valued Boolean.
You can update boolean value using UPDATE command. If you use the BOOLEAN data type, MySQL internally convert it into tinyint(1). It can takes true or false literal in which true indicates 1 to tinyint(1) and false indicates 0 to tinyint(1).
To my knowledge (correct me if I'm wrong), there is no concept of literal boolean values in SQL. You can have expressions evaluating to boolean values, but you cannot output them.
This said, you can use CASE WHEN to produce a value you can use in a comparison:
SELECT CASE WHEN ValueColumn IS NULL THEN 'FALSE' ELSE 'TRUE' END BooleanOutput FROM table If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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