修复x.2版本的更新后无法再次查询bug

nuget-publish.bat

@@ -1,8 +1,8 @@
 :start
 ::定义版本
-set EFCORE2=2.2.0.22-efcore2.1.0
-set EFCORE3=3.2.0.22
-set EFCORE5=5.2.0.22
+set EFCORE2=2.2.0.23
+set EFCORE3=3.2.0.23
+set EFCORE5=5.2.0.23
 
 ::删除所有bin与obj下的文件
 @echo off

src/ShardingCore/Sharding/AbstractShardingDbContext.cs

@@ -47,6 +47,7 @@ namespace ShardingCore.Sharding
         private DbContextOptions<T> _dbContextOptions;
 
         private readonly object CREATELOCK = new object();
+        private string connectionString;
 
         public AbstractShardingDbContext(DbContextOptions options) : base(options)
         {
@@ -97,7 +98,11 @@ namespace ShardingCore.Sharding
         }
         public string GetConnectionString()
         {
-            return Database.GetDbConnection().ConnectionString;
+            if (null == connectionString)
+            {
+                connectionString = Database.GetDbConnection().ConnectionString;
+            }
+            return connectionString;
         }