Use Php or wordpress to create a search box

I want to create a multi-function search box by using Php or wordpress program. I don't know how to implement it. I only need to perform keyword search in the last box for the general effect of the wordpress program, please kindly advise. W. use Php or wordpress to create a search box
I want to create a multi-function search box, but I don't know how to implement it. I use the wordpress program.
General Results
If you want to perform a keyword search in the last box, please kindly advise. WordPress PHP search
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1. Yes.
2. output the SQL statement and check whether the stitching is correct.
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Submit various parameters to the server. then, the server program concatenates the SQL statement and the SQL statement is OK.
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Obtain the parameters when submitting the request.
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Reference:

Reference: 1. Yes.
2. output the SQL statement and check whether the stitching is correct.


Use $ _ POST ['name'] in the background to set the name and id to unique.
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$ _ POST ['name'] is used when the background receives data.
Name is the name value of your input box.
Try this.
If (isset ($ _ POST ['name']) {
Echo $ _ POST ['name'];
}


The form sending method can be set to post or get.

For details, go to w3school.
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SQL can handle $ _ post ['text box name']
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If all input names are "s", post can only get the last value, that is, the keyword. You need to change the name of each input to a different one, and then use $ _ POST ['input name'] in the background to obtain the corresponding value.