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SQLite training in Houston TX on 2019-11-05 (details)
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Overview
Comment:Simplifications to the upper() and lower() SQL functions. Updates to documentation on sqlite3_bind_text() and sqlite3_result_text() to make it clear that users should not try to create strings with embedded NULs and that if they do the result of expression on those strings is undefined. Ticket [57c971fc74524a]
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SHA1: 9984cc20ca70b7fb39c0b99580a1317a7b0c9c85
User & Date: drh 2011-10-13 18:00:11
Context
2011-10-13
18:08
Change the makefile to delete both plain and ".exe" variants of build tools. Ticket [92bd6eaf04e117] check-in: 19536a38 user: drh tags: trunk
18:00
Simplifications to the upper() and lower() SQL functions. Updates to documentation on sqlite3_bind_text() and sqlite3_result_text() to make it clear that users should not try to create strings with embedded NULs and that if they do the result of expression on those strings is undefined. Ticket [57c971fc74524a] check-in: 9984cc20 user: drh tags: trunk
17:16
Handle updating the only row of an FTS table correctly. Fix for [9fd058691]. check-in: 7e24645b user: dan tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/func.c.

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  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){
      memcpy(z1, z2, n+1);
      for(i=0; z1[i]; i++){
        z1[i] = (char)sqlite3Toupper(z1[i]);
      }
      sqlite3_result_text(context, z1, -1, sqlite3_free);
    }
  }
}
static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  u8 *z1;
  const char *z2;
  int i, n;
  UNUSED_PARAMETER(argc);
  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){
      memcpy(z1, z2, n+1);
      for(i=0; z1[i]; i++){
        z1[i] = sqlite3Tolower(z1[i]);
      }
      sqlite3_result_text(context, (char *)z1, -1, sqlite3_free);
    }
  }
}


#if 0  /* This function is never used. */
/*







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  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){

      for(i=0; i<n; i++){
        z1[i] = (char)sqlite3Toupper(z2[i]);
      }
      sqlite3_result_text(context, z1, n, sqlite3_free);
    }
  }
}
static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  char *z1;
  const char *z2;
  int i, n;
  UNUSED_PARAMETER(argc);
  z2 = (char*)sqlite3_value_text(argv[0]);
  n = sqlite3_value_bytes(argv[0]);
  /* Verify that the call to _bytes() does not invalidate the _text() pointer */
  assert( z2==(char*)sqlite3_value_text(argv[0]) );
  if( z2 ){
    z1 = contextMalloc(context, ((i64)n)+1);
    if( z1 ){

      for(i=0; i<n; i++){
        z1[i] = sqlite3Tolower(z2[i]);
      }
      sqlite3_result_text(context, z1, n, sqlite3_free);
    }
  }
}


#if 0  /* This function is never used. */
/*

Changes to src/sqlite.h.in.

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** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes.

**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
................................................................................
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.







**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called
** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
** ^If the fifth argument is
................................................................................
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.





** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not







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** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes as this saves SQLite from having to
** make a copy of the input string.
**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
................................................................................
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.
** If a non-negative fourth parameter is provided to sqlite3_bind_text()
** or sqlite3_bind_text16() then that parameter must be the byte offset
** where the NUL terminator would occur assuming the string were NUL
** terminated.  If any NUL characters occur at byte offsets less than 
** the value of the fourth parameter then the resulting string value will
** contain embedded NULs.  The result of expressions involving strings
** with embedded NULs is undefined.
**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called
** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
** ^If the fifth argument is
................................................................................
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.  If the 3rd parameter is non-negative, then it
** must be the byte offset into the string where the NUL terminator would
** appear if the string where NUL terminated.  If any NUL characters occur
** in the string at a byte offset that is less than the value of the 3rd
** parameter, then the resulting string will contain embedded NULs and the
** result of expressions operating on strings with embedded NULs is undefined.
** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not