René Nyffenegger's collection of things on the web
René Nyffenegger on Oracle - Most wanted - Feedback -
 

SQLite wrapper

SQLiteWrapper is a C++ wrapper for SQLite.
There are some test programs that demonstrate how the SQLite Wrapper classes are used.

The implementation file

SQLiteWrapper.cpp
/* 
   SQLiteWrapper.cpp

   Copyright (C) 2004 René Nyffenegger

   This source code is provided 'as-is', without any express or implied
   warranty. In no event will the author be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this source code must not be misrepresented; you must not
      claim that you wrote the original source code. If you use this source code
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original source code.

   3. This notice may not be removed or altered from any source distribution.

   René Nyffenegger rene.nyffenegger@adp-gmbh.ch

*/

#include "SQLiteWrapper.h"
// TODO: raus
#include <windows.h>

SQLiteWrapper::SQLiteWrapper() : db_(0) {
}

bool SQLiteWrapper::Open(std::string const& db_file) {
  if (sqlite3_open(db_file.c_str(), &db_) != SQLITE_OK) {
    return false;
  }
  return true;
} 

bool SQLiteWrapper::SelectStmt(std::string const& stmt, ResultTable& res) {
  char *errmsg;
  int   ret;

  res.reset();

  ret = sqlite3_exec(db_, stmt.c_str(), SelectCallback, static_cast<void*> (&res), &errmsg);

  if (ret != SQLITE_OK) {
    return false;
  }
  return true;
//  if (ret != SQLITE_OK) {
//    std::cout << stmt << " [" << errmsg << "]" << std::endl;
//  }
}

// TODO parameter p_col_names
int SQLiteWrapper::SelectCallback(void *p_data, int num_fields, char **p_fields, char** p_col_names) {
  ResultTable* res = reinterpret_cast<ResultTable*>(p_data);

  ResultRecord record;

#ifdef SQLITE_WRAPPER_REPORT_COLUMN_NAMES
  // Hubert Castelain: column names in the first row of res if res is empty

  if(res->records_.size()==0) {
    ResultRecord col_names;

    for(int i=0; i < num_fields; i++) {
      if(p_fields[i]) col_names.fields_.push_back (p_col_names[i]);
      else
        col_names.fields_.push_back("(null)"); // or what else ?
    }
    res->records_.push_back(col_names);
  }
#endif

  for(int i=0; i < num_fields; i++) {
    // Hubert Castelain: special treatment if null
    if (p_fields[i]) record.fields_.push_back(p_fields[i]);
    else             record.fields_.push_back("<null>");
  }

  res->records_.push_back(record);

  return 0;
}

SQLiteStatement* SQLiteWrapper::Statement(std::string const& statement) {
  SQLiteStatement* stmt;
  try {
    stmt = new SQLiteStatement(statement, db_);
    return stmt;
  }
  catch (const char* e) {
    return 0;
  }
}

SQLiteStatement::SQLiteStatement(std::string const& statement, sqlite3* db) {
  if ( sqlite3_prepare(
         db, 
         statement.c_str(),  // stmt
        -1,                  // If than zero, then stmt is read up to the first nul terminator
        &stmt_,
         0                   // Pointer to unused portion of stmt
       )
       != SQLITE_OK) {
    throw sqlite3_errmsg(db);
  }

  if (!stmt_) {
    throw "stmt_ is 0";
  }
}

SQLiteStatement::~SQLiteStatement() {
  // Hubert Castelain 28/8/2005
  // Prevent the database remaining locked after some statement.
  // syntax: int sqlite3_finalize(sqlite3_stmt *pStmt);
  if(stmt_) sqlite3_finalize(stmt_);
}

SQLiteStatement::SQLiteStatement() :
  stmt_       (0)
{
}

bool SQLiteStatement::Bind(int pos_zero_indexed, std::string const& value) {
  if (sqlite3_bind_text (
         stmt_,
         pos_zero_indexed+1,  // Index of wildcard
         value.c_str(),
         value.length(),      // length of text
         SQLITE_TRANSIENT     // SQLITE_TRANSIENT: SQLite makes its own copy
         )
       != SQLITE_OK) {
     return false;
  }
  return true;
}

bool SQLiteStatement::Bind(int pos_zero_indexed, double value) {
  if (sqlite3_bind_double(
          stmt_,
          pos_zero_indexed+1,  // Index of wildcard
          value
          )
        != SQLITE_OK) {
      return false;
  }
  return true;
}

bool SQLiteStatement::Bind(int pos_zero_indexed, int value) {
  if (sqlite3_bind_int(
          stmt_,
          pos_zero_indexed+1,  // Index of wildcard
           value 
          )
        != SQLITE_OK) {
      return false;
  }
  return true;
}

bool SQLiteStatement::BindNull(int pos_zero_indexed) {
  if (sqlite3_bind_null(
          stmt_,
          pos_zero_indexed+1  // Index of wildcard
          )
        != SQLITE_OK) {
      return false;
  }
  return true;
}

bool SQLiteStatement::Execute() {
  int rc = sqlite3_step(stmt_);
  if (rc == SQLITE_BUSY) {
    ::MessageBox(0, "SQLITE_BUSY", 0, 0); 
    return false;
  }
  if (rc == SQLITE_ERROR) {
    ::MessageBox(0, "SQLITE_ERROR", 0, 0); 
    return false;
  }
  if (rc == SQLITE_MISUSE) {
    ::MessageBox(0, "SQLITE_ERROR", 0, 0); 
    return false;
  }
  if (rc != SQLITE_DONE) {
    //sqlite3_reset(stmt_);
    return false;
  }
  sqlite3_reset(stmt_);
  return true;
}

SQLiteStatement::dataType SQLiteStatement::DataType(int pos_zero_indexed) {
  return dataType(sqlite3_column_type(stmt_, pos_zero_indexed));
}

int SQLiteStatement::ValueInt(int pos_zero_indexed) {
  return sqlite3_column_int(stmt_, pos_zero_indexed);
}

std::string SQLiteStatement::ValueString(int pos_zero_indexed) {
  return std::string(reinterpret_cast<const char*>(sqlite3_column_text(stmt_, pos_zero_indexed)));
}

bool SQLiteStatement::RestartSelect() {
  sqlite3_reset(stmt_);
  return true;
}

bool SQLiteStatement::Reset() {
  int rc = sqlite3_step(stmt_);

  sqlite3_reset(stmt_);

  if (rc == SQLITE_ROW) return true;
  return false;
}

bool SQLiteStatement::NextRow() {
  int rc = sqlite3_step(stmt_);

  if (rc == SQLITE_ROW   ) {
    return true;
  }
  if (rc == SQLITE_DONE  ) {
    sqlite3_reset(stmt_);
    return false;
  } 
  else if (rc == SQLITE_MISUSE) {
    ::MessageBox(0,  "SQLiteStatement::NextRow SQLITE_MISUSE", 0, 0);
  } 
  else if (rc == SQLITE_BUSY  ) {
    ::MessageBox(0, "SQLiteStatement::NextRow SQLITE_BUSY", 0, 0);
  } 
  else if (rc == SQLITE_ERROR ) {
    ::MessageBox(0, "SQLiteStatement::NextRow SQLITE_ERROR", 0, 0);
  }
  return false;
}

bool SQLiteWrapper::DirectStatement(std::string const& stmt) {
  char *errmsg;
  int   ret;

  ret = sqlite3_exec(db_, stmt.c_str(), 0, 0, &errmsg);

  if(ret != SQLITE_OK) {
    return false;
  }
  return true;

  //if(ret != SQLITE_OK) {
  //  std::cout << stmt << " [" << errmsg << "]" << std::endl;
  //}
}

std::string SQLiteWrapper::LastError() {
  return sqlite3_errmsg(db_);
}

bool SQLiteWrapper::Begin() {
  return DirectStatement("begin");
}

bool SQLiteWrapper::Commit() {
  return DirectStatement("commit");
}

bool SQLiteWrapper::Rollback() {
  return DirectStatement("rollback");
}

The header file

SQLiteWrapper.h
/* 
   SQLiteWrapper.h

   Copyright (C) 2004 René Nyffenegger

   This source code is provided 'as-is', without any express or implied
   warranty. In no event will the author be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this source code must not be misrepresented; you must not
      claim that you wrote the original source code. If you use this source code
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original source code.

   3. This notice may not be removed or altered from any source distribution.

   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
*/

#ifndef SQLITE_WRAPPER_H__
#define SQLITE_WRAPPER_H__

#include <string>
#include <vector>

#include "sqlite3.h"

class SQLiteStatement {
  private:
    // SQLiteStatement's ctor only to be called by SQLiteWrapper
    friend class SQLiteWrapper;
    SQLiteStatement(std::string const& statement, sqlite3* db);

  public:
    SQLiteStatement();

    enum dataType {
      INT = SQLITE_INTEGER,
      FLT = SQLITE_FLOAT  ,
      TXT = SQLITE_TEXT   ,
      BLB = SQLITE_BLOB   ,
      NUL = SQLITE_NULL   ,
    };

    dataType DataType(int pos_zero_indexed);

    int         ValueInt   (int pos_zero_indexed);
    std::string ValueString(int pos_zero_indexed);

//    SQLiteStatement(const SQLiteStatement&);
   ~SQLiteStatement();

    //SQLiteStatement& operator=(SQLiteStatement const&);

    bool Bind    (int pos_zero_indexed, std::string const& value);
    bool Bind    (int pos_zero_indexed, double             value);
    bool Bind    (int pos_zero_indexed, int                value);
    bool BindNull(int pos_zero_indexed);

    bool Execute();

    bool NextRow();

    /*   Call Reset if not depending on the NextRow cleaning up.
         For example for select count(*) statements*/
    bool Reset();

    bool RestartSelect();

  private:
    //void DecreaseRefCounter();

    //int* ref_counter_; // not yet used...
    sqlite3_stmt* stmt_;
};

class SQLiteWrapper {
  public:
    SQLiteWrapper();

    bool Open(std::string const& db_file);

    class ResultRecord {
      public:
        std::vector<std::string> fields_;
    };

    class ResultTable {
      friend class SQLiteWrapper;
      public:
        ResultTable() : ptr_cur_record_(0) {}
    
        std::vector<ResultRecord> records_;
    
         ResultRecord* next() {
          if (ptr_cur_record_ < records_.size()) {
            return &(records_[ptr_cur_record_++]);
          }
          return 0;
        }
    
      private:
         void reset() {
           records_.clear();
           ptr_cur_record_=0;
         }
    
      private:
        unsigned int ptr_cur_record_;
    };

    bool SelectStmt           (std::string const& stmt, ResultTable& res);
    bool DirectStatement      (std::string const& stmt);
    SQLiteStatement* Statement(std::string const& stmt);

    std::string LastError();

    // Transaction related
    bool Begin   ();
    bool Commit  ();
    bool Rollback();

  private:

    static int SelectCallback(void *p_data, int num_fields, char **p_fields, char **p_col_names);

    sqlite3* db_;
};

#endif

Test cases

Test 1: creates a database and a table.
Test 2: inserts a record into the table without binding the value parameters.
Test 3: inserts two records into the table with binding the value parameters.
Test 4: selects * from the table and returns the selected values to the console.

Links

Joel on software reader is an application I wrote that uses this wrapper.