added flag for PIPES_AS_CONCAT connection setting for MySQL to fix #2034 (#2046)

Author: marcustut

sqlx-core/src/mysql/options/connect.rs

@@ -42,7 +42,13 @@ impl ConnectOptions for MySqlConnectOptions {
             // https://mathiasbynens.be/notes/mysql-utf8mb4
 
             let mut options = String::new();
-            options.push_str(r#"SET sql_mode=(SELECT CONCAT(@@sql_mode, ',PIPES_AS_CONCAT,NO_ENGINE_SUBSTITUTION')),"#);
+            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')),"#,
+                );
+            }
             options.push_str(r#"time_zone='+00:00',"#);
             options.push_str(&format!(
                 r#"NAMES {} COLLATE {};"#,

sqlx-core/src/mysql/options/mod.rs

@@ -65,6 +65,7 @@ pub struct MySqlConnectOptions {
     pub(crate) charset: String,
     pub(crate) collation: Option<String>,
     pub(crate) log_settings: LogSettings,
+    pub(crate) pipes_as_concat: bool,
 }
 
 impl Default for MySqlConnectOptions {
@@ -89,6 +90,7 @@ impl MySqlConnectOptions {
             ssl_ca: None,
             statement_cache_capacity: 100,
             log_settings: Default::default(),
+            pipes_as_concat: true,
         }
     }
 
@@ -212,4 +214,14 @@ impl MySqlConnectOptions {
         self.collation = Some(collation.to_owned());
         self
     }
+
+    /// Sets the flag that enables or disables the `PIPES_AS_CONCAT` connection setting
+    ///
+    /// The default value is set to true, but some MySql databases such as PlanetScale
+    /// error out with this connection setting so it needs to be set false in such
+    /// cases.
+    pub fn pipes_as_concat(mut self, flag_val: bool) -> Self {
+        self.pipes_as_concat = flag_val;
+        self
+    }
 }