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From:Michael Stassen Date:December 17 2003 7:49am
Subject:Re: Unable to insert String constants through my function
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shiva shankar wrote:

> Hi, 
> 
> I USE THIS FUNCTION TO INSERT VALUES TO DIFFERENT
> VALUES OF MY DATABASE..
> 
> 
> void InsertValues(const string &tableName, const
> string &values)
> {
>  char ValuesToStore[255];
>   long datasize;
>   char *EncodedData;
>   char *query;
> 
>   strcpy(ValuesToStore, values.c_str());
>   EncodedData = new char[strlen(ValuesToStore)*2 + 1];
>   datasize = mysql_real_escape_string(conn,
> EncodedData, ValuesToStore, strlen(ValuesToStore));
>   query = new char[datasize+255];
>   sprintf(query, "INSERT INTO %s %s VALUES %s", 
>                  tableName.c_str(),
> (lookup[tableName.c_str()]).c_str(), EncodedData); 
>   mysql_real_query(conn, query, strlen(query)+255);
> 
>   // if the insertion involves an auto-incremented
> attribute, 
>   //   the following line displays the value of that
> attribute.
>   cout << tableName << " ID inserted = " <<
> mysql_insert_id(conn) << endl;
>  cout<<query;
>   delete [] EncodedData;
>   delete [] query;
>   return;
> }
> 
> NOW WHEN I CALL THIS FUNCTION IN MAIN TO INSERT VALUES
> LIKE,
> 
> 
>   InsertValues("comm_protos", "(AwaterKent, 56)");
>   
>   InsertValues("sensor", "(1, 1, 0, 0, 0, 3, 0)");
>  
>   InsertValues("map_sensor_platform", "(1, 1)");
>   
> 
> Only the first InsertValues doesnt work,  It is unable
> to understand the string constant 'AwaterKent'
> 
> When I print out the query in InsertValues it reads as
> 
> INSERT INTO comm_protos (name, datarate) VALUES
> (AtwaterKent, 56)Values inserted into 'comm_protos'
> 
> 
> I changed to this and none of these works as well:
> 
> InsertValues("comm_protos", "('AtwaterKent', 56)");
> The query prints out as
> 
> INSERT INTO comm_protos (name, datarate) VALUES
> (\'AtwaterKent\', 56)Values inserted into
> 'comm_protos'
> 
> 
> When I tried this,
> 
> InsertValues("comm_protos", "(\'AtwaterKent\', 56)");
> 
> The query printed as:
> INSERT INTO comm_protos (name, datarate) VALUES
> (\'AtwaterKent\', 56)Values inserted into
> 'comm_protos'
> 
> 
> 
> 
> PLEASE LET ME KNOW HOW I NEED TO PASS THE STRING
> CONSTANT OR IF I NEED TO MAKE ANY CHANGE IN MY
> INSERTVALUES FUNCTION..
> 
> 
> THANKS A LOT,
> SHIV

The query needs to look like this:

INSERT INTO comm_protos (name, datarate) VALUES ('AtwaterKent', 56)

I'd say you need to fix your InsertValues function, as it mishandles 
strings.  It should either quote them, or it should expect them to 
arrive quoted and then NOT escape the quotes.  Personally, I think the 
former is better, but then the question arises as to how to tell which 
things should be quoted.  Either way, the string needs to be escaped 
before being wrapped in quotes, so that King's Cross becomes 'King\'s 
Cross' rather than 'King's Cross' or \'King\'s Cross\'.

Michael

Thread
Unable to insert String constants through my functionshiva shankar16 Dec
  • Re: Unable to insert String constants through my functionMichael Stassen17 Dec