How to repair "invalid operands of types 'const char' to binary 'operator+'?

Possible Duplicate:
How do I concatenate multiple C++ strings on one line?

According to this a C++ std::string is concatenated by using operator+. Why then does this code

using namespace std;
string sql = "create table m_table(" + 
    "path TEXT," +
    "quality REAL," +
    "found INTEGER);"; 

cause this error?

invalid operands of types 'const char [22]' and 'const char [17]' to binary 'operator+'