MySqlCommand, MySqlParameter and "LIKE" with percent symbol zt

 

Introduction

Using GetSqlStringCommand with a text comparative, with LIKE, in ADO.NET and the MySQLParamenter gets you different result between executing by hand the command in a MySQL client and executing it through ADO.NET.

Background

This occurs when you write a command like this "SELECT * FROM users WHERE name LIKE '%John%'", this will return:

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John Frank

Johnny Philips

H. F. John

But for ADO.NET if you set a var, like "@name" and update the command like this "SELECT * FROM users WHERE name LIKE '%@name%'", ADO.NET treats it as the string '@name' you will return 0 result, because no exists any user with the name @name or the email @name, but yes someone with an email of the domain "name.com", like [email protected], but this is a casualty and not, what we expect. 

 So you need to remove the simple quota and set the value appending and preceding with "%". 

Using the code 

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//Wrong way

MySQLCommand cmd = oldDb.GetSqlStringCommand(CommandType.Text,"SELECT * FROM users WHERE name LIKE '%@name%'");

MySQLParameter nameParameter= cmd.CreateParameter();

nameParameter.DbType = DbType.String;

nameParameter.ParameterName = "@name";

nameParameter.Value = "John";



//Good way

MySQLCommand cmd = oldDb.GetSqlStringCommand(CommandType.Text,"SELECT * FROM users WHERE name LIKE @name");

MySQLParameter nameParameter= cmd.CreateParameter();

nameParameter.DbType = DbType.String;

nameParameter.ParameterName = "@searchText"

nameParameter.Value = "%John%";