In SQL, the distinct keyword will allow us to do that. Here’s what the simple SQL would look like: SELECT DISTINCT employee_location from employee; Running this query will return the following results: employee
What is distinct count in SQL? The COUNT DISTINCT and COUNT UNIQUE functions return unique values. The COUNT DISTINCT functionreturns the number of unique values in the column or expression, as the following example shows. ... If the COUNT DISTINCT function encounters NULL values, it ignores th...
assuming that t1 is used before t2 (which you can check with EXPLAIN), MySQL stops reading from t2 (for any particular row in t1) when it finds the first row in t2:
Adding more columns to the query tells the query engine to find all the distinct combinations ofPET TYPESandPET GENDERS. Again, we can use either a SQL GROUP BY or DISTINCT clause to return the desired results. Please see T-SQL code below for used in this example. In our case, we have...
To learn more, visitSQL GROUP BY. DISTINCT With ORDER BY Let's take a look at an example, -- with order bySELECTDISTINCTageFROMCustomersORDERBYageDESC; Here, the SQL command selects unique ages and orders them in descending order from theCustomerstable. ...
Use the DISTINCT keyword before the column names in an SQL statement to prevent duplicate rows from being selected. Examples The following example lists only the unique divisions that exist in the Q.ORG table: This query: SELECT DISTINCT DIVISION ...
SQL statementSELECT DISTINCT(FirstName) FROM Individual;Source TableIndividualIdFirstNameLastNameUserName 1 Fred Flinstone freddo 2 Homer Simpson homey 3 Homer Brown notsofamous 4 Ozzy Ozzbourne sabbath 5 Homer Gain noplacelikeResultIn this example, using the DISTINCT keyword, all customers with the...
The above result shows the sameagent_code,ord_amountandcust_codeappears more than once in theorderstable. Example: SELECT with DISTINCT on two columns The SQL statement below retrieves identical rows based on the 'agent_code' and 'ord_amount' columns from the orders table : ...
Example 1: Use DISTINCT on one columnTo select all distinct stores in Table Store_Information, we key in,SELECT DISTINCT Store_Name FROM Store_Information;Result: Store_Name Los Angeles San Diego BostonExample 2: Use DISTINCT on multiple columns...
SQL Server中的DataLength和Len函数 example : select len(convert(varchar(50),N'狮lion')) --5 N''表示Unicode格式字符串 select datalength...Len返回字符串的字符长度,这个好理解,一个汉字'狮'+4个字母'lion'=5个字符.每个汉字和字母都占一个字符长度...DataLength返回字符串的字节长度.对于字节长度,需...