Re: bytea question
От | mjp@ornl.gov |
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Тема | Re: bytea question |
Дата | |
Msg-id | 20000815180620.B11670@grail.lsd.ornl.gov обсуждение исходный текст |
Ответ на | Re: bytea question (mikeo <mikeo@spectrumtelecorp.com>) |
Ответы |
Re: bytea question
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Список | pgsql-general |
Oops! You have to write a function for it. Here is a sample quick C function: typedef struct { int len; char data[1]; } string; string *byteatostr(bytea *arg) { char buf[1024]; int ln,i; string *res; ln = VARSIZE(arg) - VARHDRSZ; memmove(buf, VARDATA(arg), ln); for(i=0; i < ln; i++) if( buf[i] < 32 ) buf[i]='?'; res = (string *) palloc(VARHDRSZ + ln); memset(res, 0, VARHDRSZ + ln); res->len = VARHDRSZ + ln; memmove(res->data, buf, (int) ln); return res; } where all non-printable chars are replaced with '?'. Optionally, the chars can be escaped (prefixed with '\') - adjusting ln as neccessry. now you get: # select byteatostr(col) from test2; byteatostr ------------------------------------------------------------ fk_uste_wu_id?us_states?web_users?UNSPECIFIED?wu_id?wu_id? (1 rows) On Tue, Aug 15, 2000 at 05:23:38PM -0400, mikeo wrote: > thanks anyway but that doesn't work. i should've mentioned that i'd > already tried that in SQL. my apologies. > > > tig4=# \d x > Table "x" > Attribute | Type | Modifier > -----------+-------+---------- > tgargs | bytea | > > tig4=# select substr(tgargs,1,5) from x; > ERROR: Function 'substr(bytea, int4, int4)' does not exist > Unable to identify a function that satisfies the given argument types > You may need to add explicit typecasts > > tig4=# select substr(tgargs::text,1,5) from x; > ERROR: Cannot cast type 'bytea' to 'text' > > and other things like varchar, etc. > > tig4=# select * from x; > tgargs > ------------------------------------------------------------------------------ > fk_uste_wu_id\000us_states\000web_users\000UNSPECIFIED\000wu_id\000wu_id\000 > fk_uste_wu_id\000us_states\000web_users\000UNSPECIFIED\000wu_id\000wu_id\000 > fk_uste_wu_id\000us_states\000web_users\000UNSPECIFIED\000wu_id\000wu_id\000 > > what i'm looking to do here is to get the table names and column names out > using sql. i can do it in perl with a split command on '\' but was curious > as to how to "SQL" split up a BYTEA type field. > > mikeo > > > At 04:38 PM 8/15/00 -0400, mjp@ornl.gov wrote: > >Try > > > >substr(text,int4) or > >substr(text, int4, int4) > > > >For example, > > > > > >% select substr('hi there',4,3); > > substr > >-------- > > the > >(1 row) > > > >Morey Parang > >ORNL >
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