Difference Between string and String in C#.NET

There is no different between string and String (System.String). string is an alias for System.String in C#.Net.

They compile to the same code, so no difference at execution time. The complete list of aliases in C#.Net is

object:System.Object 
string:System.String
bool:System.Boolean
byte:System.Byte
sbyte:System.SByte
short:System.Int16
ushort:System.UInt16
int:System.Int32
uint:System.UInt32
long:System.Int64
ulong:System.UInt64
float:System.Single
double:System.Double
decimal:System.Decimal
char:System.Char

ORA-00254 Error in Archive Control String

Error Code
ORA-00254

Description
Error in archive control string 'string'.

Cause
Possible cause of this error is, the specified archive log location is invalid in the archive command or the LOG_ARCHIVE_DEST initialization parameter.

Action
To fix this issue, check the archive string used to make sure it refers to a valid online device.

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ORA-00253 Character Limit String Exceeded by Archive Destination

Error Code
ORA-00253

Description
Character limit string exceeded by archive destination string string.

Cause
Possible cause of this error is, the destination specified by an ALTER SYSTEM ARCHIVE LOG START TO command was too long.

Action
To fix this issue, retry the ALTER SYSTEM command using a string shorter than the limit specified in the error message.

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ORA-00252 Log String of Thread String is Empty

Error Code
ORA-00252

Description
Log string of thread string is empty, cannot archive.

Cause
Possible cause of this error is, a log must be used for redo generation before it can be archived. The specified redo log was not been used since it was introduced to the database. However it is possible that instance death during a log switch left the log empty.

Action
To fix this issue, empty logs do not need to be archived. Do not attempt to archive the redo log file.

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ORA-00251 LOG_ARCHIVE_DUPLEX_DEST cannot be the Same Destination

Error Code
ORA-00251

Description
LOG_ARCHIVE_DUPLEX_DEST cannot be the same destination as string string.

Cause
Possible cause of this error is, the destination specified by the LOG_ARCHIVE_DUPLEX_DEST parameter is the same as the destination specified by an ALTER SYSTEM ARCHIVE LOG START TO command.

Action
To fix this issue, specify a different destination for parameter LOG_ARCHIVE_DUPLEX_DEST, or specify a different destination with the ALTER SYSTEM command.

reference