Search results
25 maj 2011 · Two options: Use the LIKE keyword, along with percent signs in the string. select * from table where field like '%a%' or field like '%b%'.
6 cze 2024 · We can use the function NULLIF to compare and check if the column contains null or empty values: SELECT id, name FROM Department WHERE NULLIF(TRIM(code), '') IS NULL; The NULLIF function evaluates its two arguments, returning NULL if they are equal.
Introduction to MySQL WHERE clause. The WHERE clause allows you to specify a search condition for the rows returned by a query. The following shows the syntax of the WHERE clause: SELECT . select_list. FROM . table_name. WHERE . search_condition; Code language: SQL (Structured Query Language) (sql)
26 sty 2024 · Mastering the use of the WHERE, GROUP BY, and HAVING clauses can greatly enhance the performance and functionality of your MySQL queries. In this tutorial, we will explore these clauses, understand when and how to use them together, and see practical examples to consolidate the concepts covered.
4 sty 2011 · NULL means absence of value (i.e. there is no value), while empty string means there is a string value of zero length. For example, say you have a table to store a person' data and it contains a Gender column. You can save the values as 'Male' or 'Female'.
The SQL WHERE Clause. The WHERE clause is used to filter records. It is used to extract only those records that fulfill a specified condition. Example. Select all customers from Mexico: SELECT * FROM Customers WHERE Country='Mexico'; Try it Yourself » Syntax. SELECT column1, column2, ... FROM table_name WHERE condition;
A select_expression or where_definition in a SQL statement can consist of any expression using the functions described next. An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and functions involved in the expression.
