Add the sqlite3_result_str() interface and use it to simplify the code.

FossilOrigin-Name: 8f8361edf82233d6cd53bf8cd2f7fbf0cb3552228c9202395ef1e3383ed559ff

diff --cc manifest
index 40c7a07bd8bc0856916944b9613f30be9d3d5c06,3c3b0ff61f47f17e29297c85f21caacb765cb670..32a96f436f5f1e94d6111ef48bd567001e645d13
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Fix\sthe\sformat()\sSQL\sfunction\sso\sthat\sit\sreturns\san\sempty\sstring\snot\sa\nNULL\sif\sthe\sfirst\sargument\sis\san\sempty\sstring.\n[bugs:/info/2026-06-19T16:40:04Z|Bug\s2026-06-19T16:40:04Z]
- D 2026-06-19T16:55:08.727
 -C Use\sSQLITE_FINISH\sin\sa\sfew\splaces\sin\sthe\score,\sto\shelp\sensure\sthat\spath\sis\nwell\stested.
 -D 2026-06-19T22:57:44.085
++C Add\sthe\ssqlite3_result_str()\sinterface\sand\suse\sit\sto\ssimplify\sthe\scode.
++D 2026-06-19T23:53:29.221
  F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@@ -670,8 -670,8 +670,8 @@@ F mptest/multiwrite01.test dab5c5f8f953
  F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
  F sqlite3.1 1b9c24374a85dfc7eb8fa7c4266ee0db4f9609cceecfc5481cd8307e5af04366
  F sqlite3.pc.in e6dee284fba59ef500092fdc1843df3be8433323a3733c91da96690a50a5b398
- F src/alter.c d7cbe4332a7a2c3a21ab58ee2609efade493f6ae78254613ada0759898629ee3
- F src/analyze.c 42ed904f4a81d0e4f32491e10ff8ea3cdf2f98a29b04a015f0a29046b32b4e0f
 -F src/alter.c ff7f795c602751a574488780cfa1259f24cccbf32ddf2205b6283c0e6998ae50
++F src/alter.c da59ac700b52ba5d0e4dd099fb1818975cf8a79a546594da586b4e1eba3ae405
+ F src/analyze.c 73162482c656187823217f4c00758c9ee13a420c8745bc542129e0279b792287
  F src/attach.c c58278c7d2d954785591c4fde81669ec3e4d52f348c453b028a19ae8adf4f338
  F src/auth.c b5ece4e1edccad082c0332fa0087df225473bae0feea9269f824312201377185
  F src/backup.c 6ebe22ccbedfcb92423833992130e8d65824be4e6599c3a03f540ab38fc7d13c
@@@ -2208,8 -2208,8 +2208,9 @@@ F tool/warnings-clang.sh bbf6a1e685e534
  F tool/warnings.sh a554d13f6e5cf3760f041b87939e3d616ec6961859c3245e8ef701d1eafc2ca2
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
  F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
- P d6a3272e5592bcfeecf8a06dd8330cce57ff6603b24994b533d1fdcd48b5dc66
- R 7e7c087b6061ec959347a00d450a39f7
 -P 2fe53e6d68c3f9f1c4b064fa40fe8efe12025179a973182f0bb256acb9b5d58d
 -R 3de030f0b5267bf636ad519cf6229737
++P ece7af98a8bf982567b489cf82a52519f46a1c9360c82a486dbe1cd0664b1555 7356bf3a813bcd9082a7fdef5e2cc38c7a0f142f0ef4c948f78e4dafa216c039
++R 0fa5f372fdd27979e749925fe2796454
++T +closed 7356bf3a813bcd9082a7fdef5e2cc38c7a0f142f0ef4c948f78e4dafa216c039
  U drh
- Z 9591ba0273abaf6614bea46629e85033
 -Z e6a5bf5d9c5bcab97848f385d89977e5
++Z 40775e5df77bdbb5b520868c76d98e2b
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index 88b0ccbb10c2fdd529be5f5d24c6d4b10fd1540a,bf4b95573744c8cc2a9e1d321c52913e4f99ae31..247a0fa8bc61a1a0401c716287ad70995f3ec247
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- ece7af98a8bf982567b489cf82a52519f46a1c9360c82a486dbe1cd0664b1555
 -7356bf3a813bcd9082a7fdef5e2cc38c7a0f142f0ef4c948f78e4dafa216c039
++8f8361edf82233d6cd53bf8cd2f7fbf0cb3552228c9202395ef1e3383ed559ff

diff --cc src/alter.c
index 7e6ab325579668d3f9a742fcd60f5fe08d0b3384,a654a7cde7417e4a0a0f4d06e05cb77c52125700..7d3c85b5aed6eb03467d384951b7e6c273571df7
--- 1/src/alter.c
--- 2/src/alter.c
+++ b/src/alter.c
@@@ -2683,13 -2682,11 +2682,11 @@@ static void addConstraintFunc
  
    iOff += getWhitespace(&zSql[iOff]);
  
-   db = sqlite3_context_db_handle(ctx);
-   if( iCol<0 ){
-     zNew = sqlite3MPrintf(db, "%.*s, %s%s", iOff, zSql, zCons, &zSql[iOff]);
-   }else{
-     zNew = sqlite3MPrintf(db, "%.*s %s%s", iOff, zSql, zCons, &zSql[iOff]);
-   }
-   sqlite3_result_text(ctx, zNew, -1, SQLITE_DYNAMIC);
+   pNew = sqlite3_str_new(sqlite3_context_db_handle(ctx));
 -  sqlite3_str_append(pNew, zSql, iOff);
++  sqlite3_str_append(pNew, (const char*)zSql, iOff);
+   if( iCol<0 ) sqlite3_str_append(pNew, ",", 1);
+   sqlite3_str_appendf(pNew, " %s%s", zCons, &zSql[iOff]);
+   sqlite3_result_str(ctx, pNew, SQLITE_FINISH);
  }
  
  /*