feat(mysql): provide options to disable default connection settings a…

…fter connecting

sqlx-mysql/src/options/connect.rs

@@ -46,22 +46,35 @@ impl ConnectOptions for MySqlConnectOptions {
 
             // https://mathiasbynens.be/notes/mysql-utf8mb4
 
-            let mut options = String::new();
+            let mut sql_mode = Vec::new();
             if self.pipes_as_concat {
-                options.push_str(r#"SET sql_mode=(SELECT CONCAT(@@sql_mode, ',PIPES_AS_CONCAT,NO_ENGINE_SUBSTITUTION')),"#);
-            } else {
-                options.push_str(
-                    r#"SET sql_mode=(SELECT CONCAT(@@sql_mode, ',NO_ENGINE_SUBSTITUTION')),"#,
-                );
+                sql_mode.push(r#"PIPES_AS_CONCAT"#);
+            }
+            if self.no_engine_subsitution {
+                sql_mode.push(r#"NO_ENGINE_SUBSTITUTION"#);
+            }
+
+            let mut options = Vec::new();
+            if !sql_mode.is_empty() {
+                options.push(format!(
+                    r#"sql_mode=(SELECT CONCAT(@@sql_mode, ',{}'))"#,
+                    sql_mode.join(",")
+                ));
+            }
+            if self.set_timezone_utc {
+                options.push(r#"time_zone='+00:00'"#.to_string())
+            }
+            if self.set_names {
+                options.push(format!(
+                    r#"NAMES {} COLLATE {}"#,
+                    conn.stream.charset.as_str(),
+                    conn.stream.collation.as_str()
+                ))
+            }
+
+            if !options.is_empty() {
+                conn.execute(&*format!(r#"SET {};"#, options.join(","))).await?;
             }
-            options.push_str(r#"time_zone='+00:00',"#);
-            options.push_str(&format!(
-                r#"NAMES {} COLLATE {};"#,
-                conn.stream.charset.as_str(),
-                conn.stream.collation.as_str()
-            ));
-
-            conn.execute(&*options).await?;
 
             Ok(conn)
         })

sqlx-mysql/src/options/mod.rs

@@ -77,6 +77,10 @@ pub struct MySqlConnectOptions {
     pub(crate) log_settings: LogSettings,
     pub(crate) pipes_as_concat: bool,
     pub(crate) enable_cleartext_plugin: bool,
+
+    pub(crate) no_engine_subsitution: bool,
+    pub(crate) set_timezone_utc: bool,
+    pub(crate) set_names: bool,
 }
 
 impl Default for MySqlConnectOptions {
@@ -105,6 +109,9 @@ impl MySqlConnectOptions {
             log_settings: Default::default(),
             pipes_as_concat: true,
             enable_cleartext_plugin: false,
+            no_engine_subsitution: true,
+            set_timezone_utc: true,
+            set_names: true,
         }
     }
 
@@ -333,6 +340,43 @@ impl MySqlConnectOptions {
         self.enable_cleartext_plugin = flag_val;
         self
     }
+
+    /// Flag that enables or disables the `NO_ENGINE_SUBSTITUTION` sql_mode setting after
+    /// connection.
+    ///
+    /// If not set, if the available storage engine specified by a `CREATE TABLE` is not available,
+    /// a warning is given and the default storage engine is used instead.
+    ///
+    /// Per default this is enabled.
+    ///
+    /// https://mariadb.com/kb/en/sql-mode/
+    pub fn no_engine_subsitution(mut self, flag_val: bool) -> Self {
+        self.no_engine_subsitution = flag_val;
+        self
+    }
+
+    /// If enabled, sets `time_zone='+00:00'` after connecting with the database.
+    ///
+    /// Setting the time zone allows us to assume that the output from a TIMESTAMP field is UTC.
+    ///
+    /// Per default this is enabled.
+    pub fn set_timezone_utc(mut self, flag_val: bool) -> Self {
+        self.set_timezone_utc = flag_val;
+        self
+    }
+
+    /// If enabled, `SET NAMES 'charset_name' COLLATE 'collation_name'` is set after connecting
+    /// with the database.
+    ///
+    /// This ensures the connection uses the specified charset and encoding.
+    ///
+    /// Per default this is enabled.
+    ///
+    /// https://mathiasbynens.be/notes/mysql-utf8mb4
+    pub fn set_names(mut self, flag_val: bool) -> Self {
+        self.set_names = flag_val;
+        self
+    }
 }
 
 impl MySqlConnectOptions {