In today's blog, we'll learn some of the finer points on using UNION, along with its close cousin, UNION ALL. Having said that, if you wanted to aggregate data from similar tables that are not directly related, you can do that using the UNION operator.
So, if the input contains 1000 persons and 1000 phone numbers, the result consists of 1,000,000 pairs! Not good. That is a result set whose number of rows equals those in the first table multiplied by the number of rows in the second table. Otherwise, you risk generating a cartesian product. Normally, querying a normalized database necessitates joining tables together on one or more common fields. First the Script should connect to MySQL database and then records can be displayed.Querying Multiple Tables without Joins by Robert Gravelle Like condition has to match the entire data where as by using Regular Expression REGEXP we can match anywhere within the dataĪll above queries can be used by using PHP script. ' Our best student is Mr John Deo of 5th Class'ĬONCAT to join strings in Query Limitation of Like query In the string supplied the name is matched. Same way the query can be extended to search across more than two columns. WHERE Column1 Like '%keyword%' OR Column2 LIKE '%keyword%' Keyword should present in any columns ( by using OR ) WHERE Column1 Like '%keyword%' AND Column2 LIKE '%keyword%' Keyword should present in both columns ( by using AND ) SELECT * FROM student WHERE name LIKE 'C%' AND name NOT LIKE '_h%' Searching keyword across multiple columns by using AND, OR SELECT * FROM student WHERE name LIKE '%a%' AND name LIKE '%e%'įind all courses from the Section table that start with the character, C, but do not have h, as the second character. Name of the students having letter 'a' and letter 'e' ( without single quotes ) Try the same query by not using binary inside it. Select * from student where name LIKE binary '%A' To match lower only or upper only cases we have to use binary command to make binary matching. This way we can use LIKE command with many other commands to get desired output.Īs we have seen all the above cases are case insensitive. Using NOT with LIKE SELECT * FROM student WHERE name NOT LIKE '%John%' We can use more than one underscore also inside our query. Underscores as wildcard can be used at any location but one can replace one character only. We have used two underscores in our query to tell that first two digits can be any thing and it should end with 044. SELECT * FROM account_master WHERE acc_no LIKE '_044' For example we want to collect all the account numbers ending with 044 in a five digit account number field. We can use underscore as wildcard for one character space and use them along with LIKE statement and apply to table columns. Use of underscore ( _) as wildcard in string matching Matches string starting with j and ending with n Here is a summary of string matching using % along with LIKE query SELECT * FROM student WHERE name LIKE 'A%n' Matching string in name column starting with A and ending with n. The above result have desired word John at the end only.
SELECT * FROM student WHERE name LIKE '%John' id Here we will allow any character even zero character to the left of Have change our LIKE sql command a little by changing the % position to the end Toĭisplay the records which does not have specific word John as the beginning we We can see the result above list out all the names starting with name John. Read how Regular expression is used to Pattern matching SELECT * FROM student WHERE name LIKE 'John%' id Words we want records starting with John only. May require the names which only starts with John not inside the name. So we are getting the names those starts with John also. This will match any number of character even zero character before orĪfter the word John. The above result shows that we will get all the names where John word is present Related Tutorial Pattern match by REGEXP Keyword Search using like Locate Query
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