Don't use type conversion with String query parameters

src/Interpreters/ReplaceQueryParameterVisitor.cpp

@@ -1,6 +1,7 @@
 #include <Columns/IColumn.h>
 #include <DataTypes/DataTypeFactory.h>
 #include <DataTypes/IDataType.h>
+#include <DataTypes/DataTypeString.h>
 #include <Formats/FormatSettings.h>
 #include <IO/ReadBufferFromString.h>
 #include <Interpreters/IdentifierSemantic.h>
@@ -102,7 +103,13 @@ void ReplaceQueryParameterVisitor::visitQueryParameter(ASTPtr & ast)
     else
         literal = temp_column[0];
 
-    ast = addTypeConversionToAST(std::make_shared<ASTLiteral>(literal), type_name);
+    /// If it's a String, substitute it in the form of a string literal without CAST
+    /// to enable substitutions in simple queries that don't support expressions
+    /// (such as CREATE USER).
+    if (typeid_cast<const DataTypeString *>(data_type.get()))
+        ast = std::make_shared<ASTLiteral>(literal);
+    else
+        ast = addTypeConversionToAST(std::make_shared<ASTLiteral>(literal), type_name);
 
     /// Keep the original alias.
     ast->setAlias(alias);