1.  First we need to create a full text index for the fields we want to search (note that fields have to be of TEXT or VARCHAR type). This is done by

ALTER table1 ADD FULLTEXT (’column1′,’column2′,’…’)

2. The search query could then look like this:

SELECT *, MATCH(`column1`,`column2`) AGAINST (’$phrase’) AS relevancy

FROM table 1

WHERE  MATCH(`column1`,`column2`) AGAINST (’$phrase’)

and the result like this:

 data1   data2  data3  0.9454332

where the tailing number would be the score, or relevancy that can be used to rank search results. This is very handy and a lot more user-friendly than the rigid WHERE LIKE construct.

This is best done by using a JOIN query. How to construct the query will be explained here, step by step.

First of all, we will put the fields we want to get in the SELECT-statement, like this:

SELECT T1.C1, T1.C2, T2.C1, COUNT( T2.C3 ) AS alias1

T1 denotes table 1 and T2 table 2. C1, C2…etc denotes columns, or fields. Writing T1.C1 simply means we want to select column 1 in table one. Now the COUNT () AS statement means basically we will count the number of lines in table 2 (which we assume contains the comments) and call them alias1

FROM T1
LEFT JOIN T2 ON T1.C1 = T2.C1

Here’s the trick. Thise statment tells us which tables we are using. T1 is the main table, and then we (left) join table T2 for rows where the condition T1.C1 = T2.C1 is met. Left join is a construct that basically tells MySQL to return also NULL values (fields lacking values) .

WHERE T1.C2 = 'condition'
GROUP BY T1.C1, T1.C2, T2.C1
ORDER BY T1.C3 DESC

The rest of the statement is straight forward, stating wich results to select from table T1, how the results will be grouped and in what order they should be returned.

Here’s the full statement:

SELECT T1.C1, T1.C2, T2.C1, COUNT( T2.C3 ) AS alias1
FROM T1
LEFT JOIN T2 ON T1.C1 = T2.C1
WHERE T1.C2 = 'condition'
GROUP BY T1.C1, T1.C2, T2.C1
ORDER BY T1.C3 DESC

SELECT * FROM users WHERE age > 20 ORDER BY RAND() LIMIT1

One simple argument to the query! Awsome. Hope it helps you as much as it helped me.