The SQL ORDER BY KeywordThe ORDER BY keyword is used to sort the result-set in ascending or descending order. The ORDER BY keyword sorts the records in ascending order by default. To sort the records in descending order, use the DESC keyword.
NULL is undefined and every column can have NULL values except columns with timestamp datatype (which represent NULL values differently). So, theoretically, I agree that it is difficult to come up with the datatype of the NULL value, but in SQL Server the default datatype of the NULL is an Integer.
Feature ends with two 0's. Feature has more than two 0's. Feature has two 0's in it, at any position.
Structured Query Language
In standard SQL, a Boolean value can be TRUE , FALSE , or NULL . However, PostgreSQL is quite flexible when dealing with TRUE and FALSE values.
SQL Data Types
- Numeric data types such as int, tinyint, bigint, float, real etc.
- Date and Time data types such as Date, Time, Datetime etc.
- Character and String data types such as char, varchar, text etc.
- Unicode character string data types, for example nchar, nvarchar, ntext etc.
- Binary data types such as binary, varbinary etc.
In
SQL, a
Boolean value – either TRUE , FALSE or UNKNOWN – is a truth value.
Boolean operators.
| If the first Boolean value is: | … and the second Boolean value is: | … then the result is: |
|---|
| TRUE | TRUE | TRUE |
| TRUE | FALSE | TRUE |
| TRUE | UNKNOWN | TRUE |
| FALSE | TRUE | TRUE |
Multiple IF conditions using ELSE
- -- test if a condition is true. IF (condition is true) BEGIN.
- DO THING A. DO THING B. END.
- ELSE. BEGIN. DO THING C.
- DO THING D. DO THING E. END.
How to use distinct in SQL?
- SELECT DISTINCT returns only distinct (different) values.
- DISTINCT eliminates duplicate records from the table.
- DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc.
- DISTINCT operates on a single column.
- Multiple columns are not supported for DISTINCT.
IF…Else statement
- If the condition evaluates to True, then T-SQL statements followed by IF keyword will be executed.
- If the condition evaluates to False, then T-SQL statements followed by ELSE keyword will be executed.
IN, NOT IN operators in SQL are used with SELECT, UPDATE and DELETE statements/queries to select, update and delete only particular records in a table those meet the condition given in WHERE clause and conditions given in IN, NOT IN operators. I.e. it filters records from a table as per the condition.
MySQL does not contain built-in Boolean or Bool data type. They provide a TINYINT data type instead of Boolean or Bool data types. MySQL considered value zero as false and non-zero value as true.
How to Test for NULL Values?
- SELECT column_names. FROM table_name. WHERE column_name IS NULL;
- SELECT column_names. FROM table_name. WHERE column_name IS NOT NULL;
- Example. SELECT CustomerName, ContactName, Address. FROM Customers. WHERE Address IS NULL;
- Example. SELECT CustomerName, ContactName, Address. FROM Customers.
To insert a new value to the BIT column, use INSERT statement: INSERT INTO table_name (bit_column) VALUES (1); You can also use TRUE and FALSE as the inputs for the BIT columns, SQL Server will automatically convert them as follow: TRUE will be converted to 1.
Also, a numeric value of zero (integer or fractional), the null value ( None ), the empty string, and empty containers (i.e. lists, sets, etc.) are considered Boolean false; all other values are considered Boolean true by default.
In computer science, a boolean or bool is a data type with two possible values: true or false. It is named after the English mathematician and logician George Boole, whose algebraic and logical systems are used in all modern digital computers.
A boolean expression is an expression that results in a boolean value, that is, in a value of either true or false . The println statement will be executed if wet and cold are both true, or if poor and hungry are both true. Boolean expressions are most often used as conditions (as in the examples above).
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).
A 1-byte integer data type used in CREATE TABLE and ALTER TABLE statements. Syntax: In the column definition of a CREATE TABLE statement: column_name TINYINT. Range: -128 ..
Boolean, or boolean logic, is a subset of algebra used for creating true/false statements. Boolean expressions use the operators AND, OR, XOR, and NOT to compare values and return a true or false result.
