feat: query to fetch unique columns

Signed-off-by: Muhammad Aaqil <aaqilcs102@gmail.com>

lib/sql.js

@@ -2105,3 +2105,20 @@ SQLConnector.prototype.setNullableProperty = function(property) {
   throw new Error(g.f('{{setNullableProperty}} must be implemented by' +
   'the connector'));
 };
+
+/**
+ * Discover if database is in strict mode
+ * @param {Function} [cb] The callback function
+ */
+SQLConnector.prototype.discoverIsStrict = function(cb) {
+  const self = this;
+  const sql = self.buildQueryIsStrict();
+  this.execute(sql, cb);
+};
+
+/**
+ * Build sql for checking if database is in strict mode
+ */
+SQLConnector.prototype.buildQueryIsStrict = function() {
+  throw new Error(g.f('{{isStrict}} must be implemented by the connector'));
+};