-(void)runQuery:(const char *)query isQueryExecutable:(BOOL)queryExecutable{
// Create a sqlite object.
sqlite3 *sqlite3Database;
// Set the database file path.
NSString *databasePath = [self.documentsDirectory stringByAppendingPathComponent:self.databaseFilename];
// Initialize the results array.
if (self.arrResults != nil) {
//if(self.arrResults.count>0)
[self.arrResults removeAllObjects];
self.arrResults = nil;
}
self.arrResults = [[NSMutableArray alloc] init];
// Initialize the column names array.
if (self.arrColumnNames != nil) {
[self.arrColumnNames removeAllObjects];
self.arrColumnNames = nil;
}
self.arrColumnNames = [[NSMutableArray alloc] init];
// Open the database.
BOOL openDatabaseResult = sqlite3_open([databasePath UTF8String], &sqlite3Database);
if(openDatabaseResult == SQLITE_OK) {
// Declare a sqlite3_stmt object in which will be stored the query after having been compiled into a SQLite statement.
sqlite3_stmt *compiledStatement;
// Load all data from database to memory.
BOOL prepareStatementResult = sqlite3_prepare_v2(sqlite3Database, query, -1, &compiledStatement, NULL);
if(prepareStatementResult == SQLITE_OK) {
// Check if the query is non-executable.
if (!queryExecutable){
// In this case data must be loaded from the database.
// Declare an array to keep the data for each fetched row.
NSMutableArray *arrDataRow;
// Loop through the results and add them to the results array row by row.
while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
// Initialize the mutable array that will contain the data of a fetched row.
arrDataRow = [[NSMutableArray alloc] init];
// Get the total number of columns.
int totalColumns = sqlite3_column_count(compiledStatement);
// Go through all columns and fetch each column data.
for (int i=0; i<totalColumns; i++){
// Convert the column data to text (characters).
char *dbDataAsChars = (char *)sqlite3_column_text(compiledStatement, i);
// If there are contents in the currenct column (field) then add them to the current row array.
if (dbDataAsChars != NULL) {
// Convert the characters to string.
[arrDataRow addObject:[NSString stringWithUTF8String:dbDataAsChars]];
}else{
//added by keerti
[arrDataRow addObject:@""];
}
// Keep the current column name.
if (self.arrColumnNames.count != totalColumns) {
dbDataAsChars = (char *)sqlite3_column_name(compiledStatement, i);
[self.arrColumnNames addObject:[NSString stringWithUTF8String:dbDataAsChars]];
}
}
// Store each fetched data row in the results array, but first check if there is actually data.
if (arrDataRow.count > 0) {
[self.arrResults addObject:arrDataRow];
}
}
}
else {
// This is the case of an executable query (insert, update, ...).
// Execute the query.
bool done = sqlite3_step(compiledStatement) == SQLITE_DONE;
if (done) {
// Keep the affected rows.
self.affectedRows = sqlite3_changes(sqlite3Database);
// Keep the last inserted row ID.
self.lastInsertedRowID = sqlite3_last_insert_rowid(sqlite3Database);
}
else {
// If could not execute the query show the error message on the debugger.
NSLog(@"DB Error: %s", sqlite3_errmsg(sqlite3Database));
}
}
}
else {
// In the database cannot be opened then show the error message on the debugger.
NSLog(@"%s", sqlite3_errmsg(sqlite3Database));
}
// Release the compiled statement from memory.
sqlite3_finalize(compiledStatement);
}
// Close the database.
sqlite3_close(sqlite3Database);
}
上面是执行传递给它的查询的函数。我从多个班级调用它,但有时候我调用[self.arrResults removeAllObjects]
会导致应用程序崩溃。任何人都可以指导如何处理方案。任何帮助将不胜感激。