An article explaining the usage of thinkphp concat in detail

Developers who use ThinkPHP all know that the concat() function in ThinkPHP can concatenate multiple strings into one string. This function is very useful, especially when querying the database. This article will introduce the usage of concat() function and its examples.

Syntax and usage of concat() function

Generally, the syntax of this function is as follows:

concat(string1,string2,...)

The parameters of this function can be two or more strings. Separate parameters with commas. The concat() function concatenates these parameters into a single string and returns the result. Here is an example:

$User = M('User');
$User->where("concat(firstname,' ',lastname)='John Smith'")-> ;find();

This is a query that will find a user named John Smith in the database. This query uses the concat() function to connect the firstname and lastname fields in the database.

The concat() function can also be used to update records in the database. Here is an example:

$User = M('User');
$User->where('id=1')->save(array('username'=> concat('firstname','lastname')));

This example demonstrates how to merge two fields into one field and save it to the database.

Syntax and usage of concat_ws() function

In addition to the concat() function, ThinkPHP also provides a function called concat_ws(). The concat_ws() function inserts a delimiter between concatenated strings. The syntax is as follows:

concat_ws(separator,string1,string2,...)

The first parameter of this function is the separator. Separate parameters with commas. Here is an example:

$User = M('User');
$User->where("concat_ws(' ',firstname,lastname)='John Smith'")-> ;find();

This example is very similar to the above example, but it uses the concat_ws() function to connect firstname and lastname using spaces as separators.

Example Demonstration

It is not difficult to find that using the concat() function and the concat_ws() function statement are very similar. Reasonable selection will make the code more concise and easier to maintain.

Example

Suppose there is a user table that contains id, firstname, and lastname fields. You need to use the concat() function to concatenate firstname and lastname into a user name and query it. Suppose you want to find a user with the username "John Smith", the code is as follows:

$User = M('User');
$User->where("concat(firstname,' ',lastname)='John Smith'")->find();

Using the concat_ws() function, the same operation can be clearer:

$User = M(' User');
$User->where("concat_ws(' ',firstname,lastname)='John Smith'")->find();

In actual use, concat () function and concat_ws() function are widely used, especially when querying and updating the database. Developers can take full advantage of their features to make their code cleaner, simpler and easier to maintain.

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