utf8mb4 encoding (#7959)

* use utf8mb4 character set for connections to mysql

* use utf8mb4 character set for tables, shorten varchar fields used in unique indexes

* migration type to update table character set

* update table character sets

* set charset for temp_user.status

* gofmt

pkg/services/sqlstore/migrator/mysql_dialect.go

@@ -1,6 +1,9 @@
 package migrator
 
-import "strconv"
+import (
+	"strconv"
+	"strings"
+)
 
 type Mysql struct {
 	BaseDialect
@@ -76,6 +79,12 @@ func (db *Mysql) SqlType(c *Column) string {
 	} else if hasLen1 {
 		res += "(" + strconv.Itoa(c.Length) + ")"
 	}
+
+	switch c.Type {
+	case DB_Char, DB_Varchar, DB_NVarchar, DB_TinyText, DB_Text, DB_MediumText, DB_LongText:
+		res += " CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci"
+	}
+
 	return res
 }
 
@@ -84,3 +93,15 @@ func (db *Mysql) TableCheckSql(tableName string) (string, []interface{}) {
 	sql := "SELECT `TABLE_NAME` from `INFORMATION_SCHEMA`.`TABLES` WHERE `TABLE_SCHEMA`=? and `TABLE_NAME`=?"
 	return sql, args
 }
+
+func (db *Mysql) UpdateTableSql(tableName string, columns []*Column) string {
+	var statements = []string{}
+
+	statements = append(statements, "DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci")
+
+	for _, col := range columns {
+		statements = append(statements, "MODIFY "+col.StringNoPk(db))
+	}
+
+	return "ALTER TABLE " + db.Quote(tableName) + " " + strings.Join(statements, ", ") + ";"
+}