Re: [sqlite] How To Use ATTACH?

[Dennis Cote]

Roger Miskowicz wrote:

CppSQLite3DB db;

db.open("Stocks.db");

db.execDML("ATTACH   'Options.db' AS OPT;");

 sSQL = "UPDATE Stocks SET bOption=1 WHERE rowid IN ";
 sSQL += "(SELECT Stocks.rowid FROM Stocks, Options ";
 sSQL += "WHERE Stocks.sStockSymbol = Options.sStockSymbol); ";


  db.execDML(sSQL.c_str());

Roger,

A very minor efficiency note.

You can eliminate the runtime concatenation of your SQL strings by 
letting the compiler do it at compile time. The compiler will 
concatenate char[] constants that are separated by whitespace into a 
single char[] constant. Replacing

sSQL = "UPDATE Stocks SET bOption=1 WHERE rowid IN ";
sSQL += "(SELECT Stocks.rowid FROM Stocks, Options ";
sSQL += "WHERE Stocks.sStockSymbol = Options.sStockSymbol); ";

with

sSQL = "UPDATE Stocks SET bOption=1 WHERE rowid IN "
        "(SELECT Stocks.rowid FROM Stocks, Options "
        "WHERE Stocks.sStockSymbol = Options.sStockSymbol); ";

eliminates two unnecessary calls to the string operator+= function. I 
also think it looks better. :-)

HTH
Dennis Cote




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