How to fix CR_NO_DATA (2051): Attempt to read column without prior row fetch in MySQL

printf("Preparing statement...\n");
mysql_stmt_prepare(stmt, query, strlen(query));

printf("Binding parameters...\n");
mysql_stmt_bind_param(stmt, bind);

printf("Executing...\n");
mysql_stmt_execute(stmt);

printf("Binding results...\n");
mysql_stmt_bind_result(stmt, bind_result);

printf("Fetching row...\n");  // MUST happen before column access
int fetch_result = mysql_stmt_fetch(stmt);
if (fetch_result == 0) {
    printf("Row fetched successfully, now can access columns\n");
    // Now safe to access column data
}

// CORRECT: Fetch before accessing columns in loop
while (mysql_stmt_fetch(stmt) == 0) {
    // Now safe to access column data for this row
    mysql_stmt_fetch_column(stmt, &column_bind, 0, 0);
    // Process column data...
}

// WRONG: Trying to access columns without fetch
mysql_stmt_execute(stmt);
mysql_stmt_bind_result(stmt, bind_result);
// Missing: mysql_stmt_fetch(stmt)
mysql_stmt_fetch_column(stmt, &column_bind, 0, 0);  // CR_NO_DATA error here!

// Use mutex to protect statement operations
pthread_mutex_lock(&stmt_mutex);

mysql_stmt_execute(stmt);
mysql_stmt_bind_result(stmt, bind_result);

// Fetch MUST complete before other threads access columns
if (mysql_stmt_fetch(stmt) == 0) {
    // Column access is now safe
    mysql_stmt_fetch_column(stmt, &column_bind, 0, 0);
}

pthread_mutex_unlock(&stmt_mutex);

// Common race condition patterns to avoid:
// 1. Thread A executes, Thread B tries to read columns before A fetches
// 2. Shared statement handles without proper synchronization
// 3. Reusing statement handles across threads without resetting state

// Check all API calls for errors
if (mysql_stmt_prepare(stmt, query, strlen(query)) != 0) {
    fprintf(stderr, "Prepare failed: %s\n", mysql_stmt_error(stmt));
    return;
}

if (mysql_stmt_execute(stmt) != 0) {
    fprintf(stderr, "Execute failed: %s\n", mysql_stmt_error(stmt));
    return;
}

if (mysql_stmt_bind_result(stmt, bind_result) != 0) {
    fprintf(stderr, "Bind result failed: %s\n", mysql_stmt_error(stmt));
    return;
}

// CRITICAL: Check fetch result
int fetch_result = mysql_stmt_fetch(stmt);
if (fetch_result != 0) {
    if (fetch_result == MYSQL_NO_DATA) {
        printf("No rows returned\n");
    } else {
        fprintf(stderr, "Fetch failed: %s\n", mysql_stmt_error(stmt));
    }
    return;
}

// Now safe to access columns
if (mysql_stmt_fetch_column(stmt, &column_bind, 0, 0) != 0) {
    fprintf(stderr, "Column fetch failed: %s\n", mysql_stmt_error(stmt));
}

mysql_debug("d:t:O,/tmp/mysql.trace");

// Minimal working example
MYSQL_STMT *stmt = mysql_stmt_init(conn);
const char *query = "SELECT id, name FROM users WHERE id = ?";
mysql_stmt_prepare(stmt, query, strlen(query));

// Bind parameter
MYSQL_BIND bind_param = {0};
unsigned long param_id = 1;
bind_param.buffer_type = MYSQL_TYPE_LONG;
bind_param.buffer = &param_id;
mysql_stmt_bind_param(stmt, &bind_param);

// Execute
mysql_stmt_execute(stmt);

// Bind result
MYSQL_BIND bind_result[2] = {0};
unsigned long result_id;
char result_name[100];
unsigned long name_length;

bind_result[0].buffer_type = MYSQL_TYPE_LONG;
bind_result[0].buffer = &result_id;

bind_result[1].buffer_type = MYSQL_TYPE_STRING;
bind_result[1].buffer = result_name;
bind_result[1].buffer_length = sizeof(result_name);
bind_result[1].length = &name_length;

mysql_stmt_bind_result(stmt, bind_result);

// MUST FETCH BEFORE ACCESSING COLUMNS
if (mysql_stmt_fetch(stmt) == 0) {
    printf("User %lu: %s\n", result_id, result_name);
} else {
    printf("No data or error\n");
}

mysql_stmt_close(stmt);

mysql_config --version