This is the internal code that sqlite uses to convert the
declaration type to the REAL, INT, TEXT, BLOB types.
Happy hacking...
/*
** Each token coming out of the lexer is an instance of
** this structure. Tokens are also used as part of an expression.
**
** Note if Token.z==0 then Token.dyn and Token.n are undefined and
** may contain random values. Do not make any assuptions about Token.dyn
** and Token.n when Token.z==0.
*/
struct Token {
const unsigned char *z; /* Text of the token. Not NULL-terminated! */
unsigned dyn : 1; /* True for malloced memory, false for static */
unsigned n : 31; /* Number of characters in this token */
};
/* An array to map all upper-case characters into their corresponding
** lower-case character.
*/
const unsigned char sqlite3UpperToLower[] = {
#ifdef SQLITE_ASCII
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
252,253,254,255
#endif
#ifdef SQLITE_EBCDIC
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, /* 0x */
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, /* 1x */
32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, /* 2x */
48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, /* 3x */
64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, /* 4x */
80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, /* 5x */
96, 97, 66, 67, 68, 69, 70, 71, 72, 73,106,107,108,109,110,111, /* 6x */
112, 81, 82, 83, 84, 85, 86, 87, 88, 89,122,123,124,125,126,127, /* 7x */
128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143, /* 8x */
144,145,146,147,148,149,150,151,152,153,154,155,156,157,156,159, /* 9x */
160,161,162,163,164,165,166,167,168,169,170,171,140,141,142,175, /* Ax */
176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191, /* Bx */
192,129,130,131,132,133,134,135,136,137,202,203,204,205,206,207, /* Cx */
208,145,146,147,148,149,150,151,152,153,218,219,220,221,222,223, /* Dx */
224,225,162,163,164,165,166,167,168,169,232,203,204,205,206,207, /* Ex */
239,240,241,242,243,244,245,246,247,248,249,219,220,221,222,255, /* Fx */
#endif
};
/*
** Scan the column type name zType (length nType) and return the
** associated affinity type.
**
** This routine does a case-independent search of zType for the
** substrings in the following table. If one of the substrings is
** found, the corresponding affinity is returned. If zType contains
** more than one of the substrings, entries toward the top of
** the table take priority. For example, if zType is 'BLOBINT',
** SQLITE_AFF_INTEGER is returned.
**
** Substring | Affinity
** --------------------------------
** 'INT' | SQLITE_AFF_INTEGER
** 'CHAR' | SQLITE_AFF_TEXT
** 'CLOB' | SQLITE_AFF_TEXT
** 'TEXT' | SQLITE_AFF_TEXT
** 'BLOB' | SQLITE_AFF_NONE
** 'REAL' | SQLITE_AFF_REAL
** 'FLOA' | SQLITE_AFF_REAL
** 'DOUB' | SQLITE_AFF_REAL
**
** If none of the substrings in the above table are found,
** SQLITE_AFF_NUMERIC is returned.
*/
char sqlite3AffinityType(const Token *pType){
u32 h = 0;
char aff = SQLITE_AFF_NUMERIC;
const unsigned char *zIn = pType->z;
const unsigned char *zEnd = &pType->z[pType->n];
while( zIn!=zEnd ){
h = (h<<8) + sqlite3UpperToLower[*zIn];
zIn++;
if( h==(('c'<<24)+('h'<<16)+('a'<<8)+'r') ){ /* CHAR */
aff = SQLITE_AFF_TEXT;
}else if( h==(('c'<<24)+('l'<<16)+('o'<<8)+'b') ){ /* CLOB */
aff = SQLITE_AFF_TEXT;
}else if( h==(('t'<<24)+('e'<<16)+('x'<<8)+'t') ){ /* TEXT */
aff = SQLITE_AFF_TEXT;
}else if( h==(('b'<<24)+('l'<<16)+('o'<<8)+'b') /* BLOB */
&& (aff==SQLITE_AFF_NUMERIC || aff==SQLITE_AFF_REAL) ){
aff = SQLITE_AFF_NONE;
#ifndef SQLITE_OMIT_FLOATING_POINT
}else if( h==(('r'<<24)+('e'<<16)+('a'<<8)+'l') /* REAL */
&& aff==SQLITE_AFF_NUMERIC ){
aff = SQLITE_AFF_REAL;
}else if( h==(('f'<<24)+('l'<<16)+('o'<<8)+'a') /* FLOA */
&& aff==SQLITE_AFF_NUMERIC ){
aff = SQLITE_AFF_REAL;
}else if( h==(('d'<<24)+('o'<<16)+('u'<<8)+'b') /* DOUB */
&& aff==SQLITE_AFF_NUMERIC ){
aff = SQLITE_AFF_REAL;
#endif
}else if( (h&0x00FFFFFF)==(('i'<<16)+('n'<<8)+'t') ){ /* INT */
aff = SQLITE_AFF_INTEGER;
break;
}
}
return aff;
}
----- Original Message ----
From: Seth Falcon <[EMAIL PROTECTED]>
To: sqlite-users@sqlite.org
Sent: Tuesday, November 21, 2006 9:12:25 PM
Subject: [sqlite] A way to get SQLite type from decl type?
Hi all,
Is there a way to obtain the SQLite type (e.g. SQLITE_INTEGER) given
the declared type from the schema?
What I'm really trying to do:
I'm working on RSQLite, an interface for the R language to SQLite.
I want to determine the type of the columns in an arbitrary result
set.
Everything is fine, except when the row used to do the checking has
a NULL. In this case, I'd like to attempt to determine the type for
the column if it isn't NULL. This may not make sense to you, but
the return value I'm building is column oriented and R has special
null-like values that are type-specific.
If sqlite3_column_type returns SQLITE_NULL, I can use
sqlite3_column_decltype to obtain the declared type. But then I still
need to map that to SQLITE_INTEGER, SQLITE_REAL, or SQLITE_TEXT.
Clearly the engine knows how to do this, but I couldn't find the API
function (might just be blind ;-)
Thanks much,
+ seth
____________________________________________________________________________________
Sponsored Link
Online degrees - find the right program to advance your career.
www.nextag.com
-----------------------------------------------------------------------------
To unsubscribe, send email to [EMAIL PROTECTED]
-----------------------------------------------------------------------------
