So I asked one of my senior Dev for help to figure out Transaction scope related problem and he came to my desk and used a different overload on SqlBulkCopy and for SqlBulkCopyOptions parameter he did something like below:

```
SqlBulkCopyOptions options = (SqlBulkCopyOptions.FireTriggers | SqlBulkCopyOptions.CheckConstraints);
```

It works now, but I don't get what a `bitwise or`

means here. I thought I had some understanding of it, never really used it, but this usage made me scratch my head. Yep, I didn't ask my senior to explain it to me.. I was hoping someone could help me understand what the statement does. Most of the bitwise or examples on the net are with some numbers, which I get (I think), but this?

An enum can be used as a flag if it has the `[Flags]`

attribute and has enum values which are independent of each other:

The definition of `SqlBulkCopyOptions`

is here: https://github.com/Microsoft/referencesource/blob/master/System.Data/System/Data/SqlClient/SqlBulkCopyOptions.cs

Ignore the use of bitshift syntax. The actual values are:

```
Name Hex Dec Pow 2 Binary
Default = 0 = 0 = 0 = 00000000
KeepIdentity = 1 = 1 = 1 = 00000001
CheckConstraints = 2 = 2 = 2 = 00000010
TableLock = 4 = 4 = 3 = 00000100
KeepNulls = 8 = 8 = 4 = 00001000
FireTriggers = 10 = 16 = 5 = 00010000
UseInternalTxn = 20 = 32 = 6 = 00100000
```

Observe that each value is the next power of 2, which means in binary (last column) their bits are completely mutually exclusive.

This means you can combine them in a way that lets you see each value is set, for example, if you want `KeepIdentity`

and `TableLock`

, that's `0x01`

with `0x04`

. We use the OR operator, but on a per-bit basis, which gives us the behaviour we want:

In binary:

```
00000001
00000100 OR
--------
00000101
```

Observe how the first and third bits are now `1`

.

Thus, (`KeepIdentity | TableLock == 5`

).

This approach does not work for enum values which are not powers of two, for example, if `KeepIdentity`

had a value of `1`

and `CheckConstraints`

had a value of `2`

but `TableLock`

had a value of `3`

, then in binary they are:

```
00000001 KeepIdentity
00000010 CheckConstraints
00000011 TableLock
```

Observe that by analysing the bits of `00000011`

it is impossible to determine if this is the combination of `KeepIdentity`

and `CheckConstraints`

, or a single `TableLock`

value. This is why flags enum values must be: 1. Powers of 2, and 2: mutually-exclusive (with exceptions for shorthand and combination values).

The principle is exactly the same with an `enum`

as it is with numbers, as the underlying type of an `enum`

is always an integral type. If you look at the declaration of `SqlBulkCopyOptions`

, you'll see that its members have underlying values that are powers of two so that they can be combined in this way.

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