Pepares the SQL statement and saves the resulting sqlite3_stmt object inĪssociating it with a tag ("emp-by-last").Printf ("Rows retrieved: %d\n", ctx->count) If (ctx->rc != SQLITE_DONE) printf ("Error retrieving data") While (sps_next_row 3(ctx,"itti",&emp_num,&first,&last,&dept_num)) "SELECT * FROM employee WHERE last LIKE ?1", "s") Ĭtx = sps_execute 2 (sps, "emp-by-last","%son") Simplicity of sqlite3_exec() and tediousness of the standard prepare,bind,step,column_xxx loop. I wrote my own support library that lets my applications deal with SQLite in a style in between the As we know, having something work by luck is often a form of bad luck. Doing that might have worked, but only by luck.
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It is because zSql (and zTail) point to possibly multi-byte character representations that my suggested code did not do simple pointer arithmetic. Substring() method can be safely used without having to anticipate that the UTF-16 encoding used for CLR String objects will result in some other number of characters being lopped off or that a UTF-16 code point representation will be sliced into pieces. Substring(int startIndex) method, where that index is not a count of UTF-16 words but is a zero-based "character position".
Computing the accepted number of "characters" (or UTF-8 code points) has nothing to do with C# at that level, with this tiny proviso: Once control gets back to the C# domain, where we can presume the multi-statement string appears as a CLR String type, it is quite easy to lop off the accepted portion using the. I have no expectation of luck or desire to rely on it.Īt the point I suggested, to the OP, a way of knowing how much of a multi-statement string was accepted by sqlite3_prepare, the "strings" are simple char* but known to be referencing UTF-8 code sequences. With very similar memory allocation, you could just extract the single SQL statements from the statement glom and do the prepare/step/finalize on each one. Your possibly neat workaround could be made to work. (It does not support them in quite the manner you are thinking, but it does support the work-around that I suggested earlier.) I would bet long odds against that happening, particularly because the existing API already permits the operations you would like to perform. There is no way for a heretofore nonexistent SQLite API to later "return the remaining portion of the SQL" unless the connection were to store it away for future reference, which would also require a way to cease storing it. My point is that is probably does not upon return to the C# call site. The issue is whether that pointer points to something that can be referenced. The pointer is nothing more than a single value, easily passed by value. If that is the case, then an API to return the remaining portion of the SQL would be handy. To me that suggests that the pointer is still alive in the DLL. That would be a simple C expression too trivial to merit an API entry. Is there an SQLite3 function to retrieve the string from the pointer **pzTail? The means of copying C string content to C# string objects should be easily found (and they are off-topic here.) If you have control of the adapter layer between the C# interface and the SQLite C library, you could create there a new C# string reflecting the content portion referenced by pzTail, and make that an out parameter of the C# interface. Hence, the pzTail value coming out of the C-level call will be referencing memory that likely will not be allocated to hold zSql content when the C# calling code regains control. But at the C# calling level, the string parameter passed whose content ultimately becomes something referenced by a zSql is likely to be stored in a temporary whose lifetime expires before or during the return to the C# calling context. At the C API level, it will be pointing within the range of chars referenced by zSql. That said, there is not going to be a good way to use that pzTail out pointer from the C# calling context. This is more of a C# question than a SQLite API question.
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