String literals.

Author: cincuranet

Provider/src/FirebirdSql.EntityFrameworkCore.Firebird.Tests/Migrations/MigrationsTests.cs

@@ -91,7 +91,7 @@ public void CreateTable()
 							Table = "People",
 							ClrType = typeof(string),
 							MaxLength = 20,
-							DefaultValueSql = "''",
+							DefaultValueSql = "'x'",
 							IsNullable = true,
 						},
 				},
@@ -122,8 +122,8 @@ public void CreateTable()
     ""Id_Sequence"" INTEGER NOT NULL,
     ""EmployerId"" INTEGER,
     ""SSN"" char(11),
-    ""DEF_O"" VARCHAR(20) DEFAULT _UTF8'test',
-    ""DEF_S"" VARCHAR(20) DEFAULT (''),
+    ""DEF_O"" VARCHAR(20) DEFAULT CAST(_UTF8'test' as VARCHAR(4) CHARACTER SET UTF8),
+    ""DEF_S"" VARCHAR(20) DEFAULT ('x'),
     PRIMARY KEY (""Id""),
     UNIQUE (""SSN""),
     FOREIGN KEY (""EmployerId"") REFERENCES ""Companies"" (""Id"") ON UPDATE NO ACTION ON DELETE NO ACTION

Provider/src/FirebirdSql.EntityFrameworkCore.Firebird/Storage/Internal/FbStringTypeMapping.cs

@@ -38,9 +38,12 @@ protected override void ConfigureParameter(DbParameter parameter)
 
 		protected override string GenerateNonNullSqlLiteral(object value)
 		{
+			var svalue = (string)value;
+			if (svalue == string.Empty)
+				return "''";
 			return IsUnicode
-				? $"_UTF8'{EscapeSqlLiteral((string)value)}'"
-				: $"'{EscapeSqlLiteral((string)value)}'";
+				? $"CAST(_UTF8'{EscapeSqlLiteral(svalue)}' as VARCHAR({svalue.Length}) CHARACTER SET UTF8)"
+				: $"CAST('{EscapeSqlLiteral(svalue)}' as VARCHAR({svalue.Length}))";
 		}
 	}
 }