> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/server-programming/spi/spi-interface-support/spi-spi-fnumber.md).

# SPI\_fnumber

### SPI\_fnumber

SPI\_fnumber — determine the column number for the specified column name

### Synopsis

```

int SPI_fnumber(TupleDesc rowdesc, const char * colname)
```

### Description

`SPI_fnumber` returns the column number for the column with the specified name.

If *`colname`* refers to a system column (e.g., `ctid`) then the appropriate negative column number will be returned. The caller should be careful to test the return value for exact equality to `SPI_ERROR_NOATTRIBUTE` to detect an error; testing the result for less than or equal to 0 is not correct unless system columns should be rejected.

### Arguments

`TupleDesc rowdesc` : input row description

`const char * colname` : column name

### Return Value

Column number (count starts at 1 for user-defined columns), or `SPI_ERROR_NOATTRIBUTE` if the named column was not found.

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/spi-spi-fnumber.html)（英文原文，待翻譯）


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