- 完善 $"{a.Code}_{a.Id}" lambda 解析，防止 null 相连；

28810 · 28810 · commit e80f1796638d · 2020-07-26T09:34:49.000+08:00
diff --git a/FreeSql.DbContext/FreeSql.DbContext.xml b/FreeSql.DbContext/FreeSql.DbContext.xml
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.MySqlConnector/MySqlConnector/MySqlConnectorExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.MySqlConnector/MySqlConnector/MySqlConnectorExpression/StringTest.cs
@@ -61,7 +61,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT concat('x',(a.`Id` + 1),'z-',date_format(a.`CreateTime`,'%Y%m'),'',a.`Title`,'') as1, concat('',(a.`Id` + 1),'x',(a.`Id` + 1),'z-',date_format(a.`CreateTime`,'%Y%m'),'',a.`Title`,'') as2 
+            Assert.Equal($@"SELECT concat('x',ifnull((a.`Id` + 1), ''),'z-',ifnull(date_format(a.`CreateTime`,'%Y%m'), ''),'',ifnull(a.`Title`, ''),'') as1, concat('',ifnull((a.`Id` + 1), ''),'x',ifnull((a.`Id` + 1), ''),'z-',ifnull(date_format(a.`CreateTime`,'%Y%m'), ''),'',ifnull(a.`Title`, ''),'') as2 
 FROM `tb_topic` a 
 WHERE (a.`Id` = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/Dameng/DamengExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/Dameng/DamengExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as1, ''||((a.""ID"" + 1))||'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as1, ''||nvl((a.""ID"" + 1), '')||'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as2 
 FROM ""TB_TOPIC"" a 
 WHERE (a.""ID"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/KingbaseES/KingbaseESExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/KingbaseES/KingbaseESExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""ID"" + 1))||'z-'||(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'))||''||(a.""TITLE"")||'' as1, ''||((a.""ID"" + 1))||'x'||((a.""ID"" + 1))||'z-'||(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'))||''||(a.""TITLE"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||coalesce(((a.""ID"" + 1))::text, '')||'z-'||coalesce(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""TITLE"", '')||'' as1, ''||coalesce(((a.""ID"" + 1))::text, '')||'x'||coalesce(((a.""ID"" + 1))::text, '')||'z-'||coalesce(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""TITLE"", '')||'' as2 
 FROM ""TB_TOPIC"" a 
 WHERE (a.""ID"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/MySql/MySqlExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/MySql/MySqlExpression/StringTest.cs
@@ -61,7 +61,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT concat('x',(a.`Id` + 1),'z-',date_format(a.`CreateTime`,'%Y%m'),'',a.`Title`,'') as1, concat('',(a.`Id` + 1),'x',(a.`Id` + 1),'z-',date_format(a.`CreateTime`,'%Y%m'),'',a.`Title`,'') as2 
+            Assert.Equal($@"SELECT concat('x',ifnull((a.`Id` + 1), ''),'z-',ifnull(date_format(a.`CreateTime`,'%Y%m'), ''),'',ifnull(a.`Title`, ''),'') as1, concat('',ifnull((a.`Id` + 1), ''),'x',ifnull((a.`Id` + 1), ''),'z-',ifnull(date_format(a.`CreateTime`,'%Y%m'), ''),'',ifnull(a.`Title`, ''),'') as2 
 FROM `tb_topic` a 
 WHERE (a.`Id` = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/Oracle/OracleExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/Oracle/OracleExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as1, ''||((a.""ID"" + 1))||'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as1, ''||nvl((a.""ID"" + 1), '')||'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as2 
 FROM ""TB_TOPIC"" a 
 WHERE (a.""ID"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/PostgreSQL/PostgreSQLExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/PostgreSQL/PostgreSQLExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""id"" + 1))||'z-'||(to_char((a.""createtime"")::timestamp,'YYYYMM'))||''||(a.""title"")||'' as1, ''||((a.""id"" + 1))||'x'||((a.""id"" + 1))||'z-'||(to_char((a.""createtime"")::timestamp,'YYYYMM'))||''||(a.""title"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||coalesce(((a.""id"" + 1))::text, '')||'z-'||coalesce(to_char((a.""createtime"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""title"", '')||'' as1, ''||coalesce(((a.""id"" + 1))::text, '')||'x'||coalesce(((a.""id"" + 1))::text, '')||'z-'||coalesce(to_char((a.""createtime"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""title"", '')||'' as2 
 FROM ""tb_topic"" a 
 WHERE (a.""id"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/SqlServer/SqlServerExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/SqlServer/SqlServerExpression/StringTest.cs
@@ -60,7 +60,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT N'x'+cast((a.[Id] + 1) as varchar)+N'z-'+(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6))+N''+(a.[Title])+N'' as1, N''+cast((a.[Id] + 1) as varchar)+N'x'+cast((a.[Id] + 1) as varchar)+N'z-'+(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6))+N''+(a.[Title])+N'' as2 
+            Assert.Equal($@"SELECT N'x'+isnull(cast((a.[Id] + 1) as varchar), '')+N'z-'+isnull(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6), '')+N''+isnull(a.[Title], '')+N'' as1, N''+isnull(cast((a.[Id] + 1) as varchar), '')+N'x'+isnull(cast((a.[Id] + 1) as varchar), '')+N'z-'+isnull(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6), '')+N''+isnull(a.[Title], '')+N'' as2 
 FROM [tb_topic] a 
 WHERE (a.[Id] = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/Dameng/DamengExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/Dameng/DamengExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as1, ''||((a.""ID"" + 1))||'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as1, ''||nvl((a.""ID"" + 1), '')||'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as2 
 FROM ""TB_TOPIC"" a 
 WHERE (a.""ID"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/MsAccess/MsAccessExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/MsAccess/MsAccessExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'+cstr((a.[Id] + 1))+'z-'+(format(a.[CreateTime],'yyyyMM'))+''+(a.[Title])+'' as as1, ''+cstr((a.[Id] + 1))+'x'+cstr((a.[Id] + 1))+'z-'+(format(a.[CreateTime],'yyyyMM'))+''+(a.[Title])+'' as as2 
+            Assert.Equal($@"SELECT 'x'+iif(isnull(cstr((a.[Id] + 1))), '', cstr((a.[Id] + 1)))+'z-'+iif(isnull(format(a.[CreateTime],'yyyyMM')), '', format(a.[CreateTime],'yyyyMM'))+''+iif(isnull(a.[Title]), '', a.[Title])+'' as as1, ''+iif(isnull(cstr((a.[Id] + 1))), '', cstr((a.[Id] + 1)))+'x'+iif(isnull(cstr((a.[Id] + 1))), '', cstr((a.[Id] + 1)))+'z-'+iif(isnull(format(a.[CreateTime],'yyyyMM')), '', format(a.[CreateTime],'yyyyMM'))+''+iif(isnull(a.[Title]), '', a.[Title])+'' as as2 
 FROM [tb_topic] a 
 WHERE (a.[Id] = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/MySql/MySqlExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/MySql/MySqlExpression/StringTest.cs
@@ -61,7 +61,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT concat('x',(a.`Id` + 1),'z-',date_format(a.`CreateTime`,'%Y%m'),'',a.`Title`,'') as1, concat('',(a.`Id` + 1),'x',(a.`Id` + 1),'z-',date_format(a.`CreateTime`,'%Y%m'),'',a.`Title`,'') as2 
+            Assert.Equal($@"SELECT concat('x',ifnull((a.`Id` + 1), ''),'z-',ifnull(date_format(a.`CreateTime`,'%Y%m'), ''),'',ifnull(a.`Title`, ''),'') as1, concat('',ifnull((a.`Id` + 1), ''),'x',ifnull((a.`Id` + 1), ''),'z-',ifnull(date_format(a.`CreateTime`,'%Y%m'), ''),'',ifnull(a.`Title`, ''),'') as2 
 FROM `tb_topic` a 
 WHERE (a.`Id` = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/Oracle/OracleExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/Oracle/OracleExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as1, ''||((a.""ID"" + 1))||'x'||((a.""ID"" + 1))||'z-'||(to_char(a.""CREATETIME"",'YYYYMM'))||''||(a.""TITLE"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as1, ''||nvl((a.""ID"" + 1), '')||'x'||nvl((a.""ID"" + 1), '')||'z-'||nvl(to_char(a.""CREATETIME"",'YYYYMM'), '')||''||nvl(a.""TITLE"", '')||'' as2 
 FROM ""TB_TOPIC"" a 
 WHERE (a.""ID"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/PostgreSQL/PostgreSQLExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/PostgreSQL/PostgreSQLExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""id"" + 1))||'z-'||(to_char((a.""createtime"")::timestamp,'YYYYMM'))||''||(a.""title"")||'' as1, ''||((a.""id"" + 1))||'x'||((a.""id"" + 1))||'z-'||(to_char((a.""createtime"")::timestamp,'YYYYMM'))||''||(a.""title"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||coalesce(((a.""id"" + 1))::text, '')||'z-'||coalesce(to_char((a.""createtime"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""title"", '')||'' as1, ''||coalesce(((a.""id"" + 1))::text, '')||'x'||coalesce(((a.""id"" + 1))::text, '')||'z-'||coalesce(to_char((a.""createtime"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""title"", '')||'' as2 
 FROM ""tb_topic"" a 
 WHERE (a.""id"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/ShenTong/ShenTongExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/ShenTong/ShenTongExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""ID"" + 1))||'z-'||(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'))||''||(a.""TITLE"")||'' as1, ''||((a.""ID"" + 1))||'x'||((a.""ID"" + 1))||'z-'||(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'))||''||(a.""TITLE"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||coalesce((a.""ID"" + 1), '')||'z-'||coalesce(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""TITLE"", '')||'' as1, ''||coalesce((a.""ID"" + 1), '')||'x'||coalesce((a.""ID"" + 1), '')||'z-'||coalesce(to_char((a.""CREATETIME"")::timestamp,'YYYYMM'), '')||''||coalesce(a.""TITLE"", '')||'' as2 
 FROM ""TB_TOPIC"" a 
 WHERE (a.""ID"" = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/SqlServer/SqlServerExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/SqlServer/SqlServerExpression/StringTest.cs
@@ -74,7 +74,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT N'x'+cast((a.[Id] + 1) as varchar)+N'z-'+(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6))+N''+(a.[Title])+N'' as1, N''+cast((a.[Id] + 1) as varchar)+N'x'+cast((a.[Id] + 1) as varchar)+N'z-'+(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6))+N''+(a.[Title])+N'' as2 
+            Assert.Equal($@"SELECT N'x'+isnull(cast((a.[Id] + 1) as varchar), '')+N'z-'+isnull(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6), '')+N''+isnull(a.[Title], '')+N'' as1, N''+isnull(cast((a.[Id] + 1) as varchar), '')+N'x'+isnull(cast((a.[Id] + 1) as varchar), '')+N'z-'+isnull(substring(convert(char(8), cast(a.[CreateTime] as datetime), 112), 1, 6), '')+N''+isnull(a.[Title], '')+N'' as2 
 FROM [tb_topic] a 
 WHERE (a.[Id] = {item.Id})", sql);
 
diff --git a/FreeSql.Tests/FreeSql.Tests/Sqlite/SqliteExpression/StringTest.cs b/FreeSql.Tests/FreeSql.Tests/Sqlite/SqliteExpression/StringTest.cs
@@ -59,7 +59,7 @@ public void Format()
                 str = $"x{a.Id + 1}z-{a.CreateTime.ToString("yyyyMM")}{a.Title}",
                 str2 = string.Format("{0}x{0}z-{1}{2}", a.Id + 1, a.CreateTime.ToString("yyyyMM"), a.Title)
             });
-            Assert.Equal($@"SELECT 'x'||((a.""Id"" + 1))||'z-'||(strftime('%Y%m',a.""CreateTime""))||''||(a.""Title"")||'' as1, ''||((a.""Id"" + 1))||'x'||((a.""Id"" + 1))||'z-'||(strftime('%Y%m',a.""CreateTime""))||''||(a.""Title"")||'' as2 
+            Assert.Equal($@"SELECT 'x'||ifnull((a.""Id"" + 1), '')||'z-'||ifnull(strftime('%Y%m',a.""CreateTime""), '')||''||ifnull(a.""Title"", '')||'' as1, ''||ifnull((a.""Id"" + 1), '')||'x'||ifnull((a.""Id"" + 1), '')||'z-'||ifnull(strftime('%Y%m',a.""CreateTime""), '')||''||ifnull(a.""Title"", '')||'' as2 
 FROM ""tb_topic"" a 
 WHERE (a.""Id"" = {item.Id})", sql);
 
diff --git a/Providers/FreeSql.Provider.Dameng/DamengExpression.cs b/Providers/FreeSql.Provider.Dameng/DamengExpression.cs
@@ -252,7 +252,7 @@ public override string ExpressionLambdaToSqlCallString(MethodCallExpression exp,
                         return _common.StringConcat(exp.Arguments.Select(a => getExp(a)).ToArray(), null);
                     case "Format":
                         if (exp.Arguments[0].NodeType != ExpressionType.Constant) throw new Exception($"未实现函数表达式 {exp} 解析，参数 {exp.Arguments[0]} 必须为常量");
-                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"'||({ExpressionLambdaToSql(a, tsc)})||'").ToArray();
+                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"'||{_common.IsNull(ExpressionLambdaToSql(a, tsc), "''")}||'").ToArray();
                         return string.Format(ExpressionLambdaToSql(exp.Arguments[0], tsc), expArgs);
                 }
             }
diff --git a/Providers/FreeSql.Provider.MsAccess/MsAccessExpression.cs b/Providers/FreeSql.Provider.MsAccess/MsAccessExpression.cs
@@ -222,7 +222,12 @@ public override string ExpressionLambdaToSqlCallString(MethodCallExpression exp,
                         return _common.StringConcat(exp.Arguments.Select(a => getExp(a)).ToArray(), exp.Arguments.Select(a => a.Type).ToArray());
                     case "Format":
                         if (exp.Arguments[0].NodeType != ExpressionType.Constant) throw new Exception($"未实现函数表达式 {exp} 解析，参数 {exp.Arguments[0]} 必须为常量");
-                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"'+{(((a as UnaryExpression)?.Operand.Type ?? a.Type) == typeof(string) ? $"({ExpressionLambdaToSql(a, tsc)})" : $"cstr({ExpressionLambdaToSql(a, tsc)})")}+'").ToArray();
+                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a =>
+                        {
+                            var asql = ((a as UnaryExpression)?.Operand.Type ?? a.Type) == typeof(string) ? $"{ExpressionLambdaToSql(a, tsc)}" : $"cstr({ExpressionLambdaToSql(a, tsc)})";
+                            return $"'+{_common.IsNull(asql, "''")}+'";
+                        }
+                        ).ToArray();
                         return string.Format(ExpressionLambdaToSql(exp.Arguments[0], tsc), expArgs);
                 }
             }
diff --git a/Providers/FreeSql.Provider.MySql/MySqlExpression.cs b/Providers/FreeSql.Provider.MySql/MySqlExpression.cs
@@ -251,7 +251,7 @@ public override string ExpressionLambdaToSqlCallString(MethodCallExpression exp,
                     case "Format":
                         if (exp.Arguments[0].NodeType != ExpressionType.Constant) throw new Exception($"未实现函数表达式 {exp} 解析，参数 {exp.Arguments[0]} 必须为常量");
                         if (exp.Arguments.Count == 1) return ExpressionLambdaToSql(exp.Arguments[0], tsc);
-                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"',{ExpressionLambdaToSql(a, tsc)},'").ToArray();
+                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"',{_common.IsNull(ExpressionLambdaToSql(a, tsc), "''")},'").ToArray();
                         return $"concat({string.Format(ExpressionLambdaToSql(exp.Arguments[0], tsc), expArgs)})";
                 }
             }
diff --git a/Providers/FreeSql.Provider.Odbc/Dameng/OdbcDamengExpression.cs b/Providers/FreeSql.Provider.Odbc/Dameng/OdbcDamengExpression.cs
@@ -252,7 +252,7 @@ public override string ExpressionLambdaToSqlCallString(MethodCallExpression exp,
                         return _common.StringConcat(exp.Arguments.Select(a => getExp(a)).ToArray(), null);
                     case "Format":
                         if (exp.Arguments[0].NodeType != ExpressionType.Constant) throw new Exception($"未实现函数表达式 {exp} 解析，参数 {exp.Arguments[0]} 必须为常量");
-                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"'||({ExpressionLambdaToSql(a, tsc)})||'").ToArray();
+                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"'||{_common.IsNull(ExpressionLambdaToSql(a, tsc), "''")}||'").ToArray();
                         return string.Format(ExpressionLambdaToSql(exp.Arguments[0], tsc), expArgs);
                 }
             }
diff --git a/Providers/FreeSql.Provider.Odbc/KingbaseES/OdbcKingbaseESExpression.cs b/Providers/FreeSql.Provider.Odbc/KingbaseES/OdbcKingbaseESExpression.cs
@@ -316,7 +316,12 @@ public override string ExpressionLambdaToSqlCallString(MethodCallExpression exp,
                         return _common.StringConcat(exp.Arguments.Select(a => getExp(a)).ToArray(), null);
                     case "Format":
                         if (exp.Arguments[0].NodeType != ExpressionType.Constant) throw new Exception($"未实现函数表达式 {exp} 解析，参数 {exp.Arguments[0]} 必须为常量");
-                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a => $"'||({ExpressionLambdaToSql(a, tsc)})||'").ToArray();
+                        var expArgs = exp.Arguments.Where((a, z) => z > 0).Select(a =>
+                        {
+                            var atype = (a as UnaryExpression)?.Operand.Type.NullableTypeOrThis() ?? a.Type.NullableTypeOrThis();
+                            if (atype == typeof(string)) return $"'||{_common.IsNull(ExpressionLambdaToSql(a, tsc), "''")}||'";
+                            return $"'||{_common.IsNull($"({ExpressionLambdaToSql(a, tsc)})::text", "''")}||'";
+                        }).ToArray();
                         return string.Format(ExpressionLambdaToSql(exp.Arguments[0], tsc), expArgs);
                 }
             }
diff --git a/Providers/FreeSql.Provider.Odbc/MySql/OdbcMySqlExpression.cs b/Providers/FreeSql.Provider.Odbc/MySql/OdbcMySqlExpression.cs
diff --git a/Providers/FreeSql.Provider.Odbc/Oracle/OdbcOracleExpression.cs b/Providers/FreeSql.Provider.Odbc/Oracle/OdbcOracleExpression.cs
diff --git a/Providers/FreeSql.Provider.Odbc/PostgreSQL/OdbcPostgreSQLExpression.cs b/Providers/FreeSql.Provider.Odbc/PostgreSQL/OdbcPostgreSQLExpression.cs
diff --git a/Providers/FreeSql.Provider.Odbc/SqlServer/OdbcSqlServerExpression.cs b/Providers/FreeSql.Provider.Odbc/SqlServer/OdbcSqlServerExpression.cs
diff --git a/Providers/FreeSql.Provider.Oracle/OracleExpression.cs b/Providers/FreeSql.Provider.Oracle/OracleExpression.cs
diff --git a/Providers/FreeSql.Provider.PostgreSQL/PostgreSQLExpression.cs b/Providers/FreeSql.Provider.PostgreSQL/PostgreSQLExpression.cs
diff --git a/Providers/FreeSql.Provider.ShenTong/ShenTongExpression.cs b/Providers/FreeSql.Provider.ShenTong/ShenTongExpression.cs
diff --git a/Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs b/Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs
diff --git a/Providers/FreeSql.Provider.Sqlite/SqliteExpression.cs b/Providers/FreeSql.Provider.Sqlite/SqliteExpression.cs
