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Overview
Comment: | Updates to the documentation on the sqlite3_create_function() family of interfaces. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
9d277e0b82ff8759369b43ee5f2e5628 |
User & Date: | drh 2010-09-10 16:38:30.000 |
Context
2010-09-10
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19:18 | Add tests to e_select.test. (check-in: 3a051a76f7 user: dan tags: trunk) | |
16:38 | Updates to the documentation on the sqlite3_create_function() family of interfaces. (check-in: 9d277e0b82 user: drh tags: trunk) | |
13:23 | Make sure SQLite is running with MEMSTATUS enabled at the beginning of every test script. (check-in: 6999531405 user: drh tags: trunk) | |
Changes
Changes to src/sqlite.h.in.
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3286 3287 3288 3289 3290 3291 3292 | /* ** CAPI3REF: Create Or Redefine SQL Functions ** KEYWORDS: {function creation routines} ** KEYWORDS: {application-defined SQL function} ** KEYWORDS: {application-defined SQL functions} ** | | | > | < | > | | | | | | | > | 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 | /* ** CAPI3REF: Create Or Redefine SQL Functions ** KEYWORDS: {function creation routines} ** KEYWORDS: {application-defined SQL function} ** KEYWORDS: {application-defined SQL functions} ** ** ^These functions (collectively known as "function creation routines") ** are used to add SQL functions or aggregates or to redefine the behavior ** of existing SQL functions or aggregates. The only differences between ** these routines are the text encoding expected for ** the the second parameter (the name of the function being created) ** and the presence or absence of a destructor callback for ** the application data pointer. ** ** ^The first parameter is the [database connection] to which the SQL ** function is to be added. ^If an application uses more than one database ** connection then application-defined SQL functions must be added ** to each database connection separately. ** ** ^The second parameter is the name of the SQL function to be created or ** redefined. ^The length of the name is limited to 255 bytes, exclusive of ** the zero-terminator. ^Note that the name length limit is in bytes, not ** characters. ^Any attempt to create a function with a longer name ** will result in [SQLITE_ERROR] being returned. ** ** ^The third parameter (nArg) ** is the number of arguments that the SQL function or ** aggregate takes. ^If this parameter is -1, then the SQL function or ** aggregate may take any number of arguments between 0 and the limit ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third ** parameter is less than -1 or greater than 127 then the behavior is ** undefined. ** ** ^The fourth parameter, eTextRep, specifies what ** [SQLITE_UTF8 | text encoding] this SQL function prefers for ** its parameters. Any SQL function implementation should be able to work ** work with UTF-8, UTF-16le, or UTF-16be. But some implementations may be ** more efficient with one encoding than another. ^An application may ** invoke sqlite3_create_function() or sqlite3_create_function16() multiple ** times with the same function but with different values of eTextRep. ** ^When multiple implementations of the same function are available, SQLite ** will pick the one that involves the least amount of data conversion. ** If there is only a single implementation which does not care what text ** encoding is used, then the fourth argument should be [SQLITE_ANY]. ** ** ^(The fifth parameter is an arbitrary pointer. The implementation of the ** function can gain access to this pointer using [sqlite3_user_data()].)^ ** ** ^The seventh, eighth and ninth parameters, xFunc, xStep and xFinal, are ** pointers to C-language functions that implement the SQL function or ** aggregate. ^A scalar SQL function requires an implementation of the xFunc ** callback only; NULL pointers must be passed as the xStep and xFinal ** parameters. ^An aggregate SQL function requires an implementation of xStep ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing ** SQL function or aggregate, pass NULL poiners for all three function ** callbacks. ** ** ^It is permitted to register multiple implementations of the same ** functions with the same name but with either differing numbers of ** arguments or differing preferred text encodings. ^SQLite will use ** the implementation that most closely matches the way in which the ** SQL function is used. ^A function implementation with a non-negative ** nArg parameter is a better match than a function implementation with |
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