return resultset from function
I need to return a resultset from function and work with this resultset just like with an ordinary table.
So I need something like following:
select
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If I understand you correctly, you want to do this:
select * from (select * from dual)...with the caveat that the subquery is in some way dynamic? You can do this using a PL/SQL block, using a reference cursor:
declare subQuery varchar2(1000); mainQuery varchar2(1000) := 'select * from ('; type myRefCursor is ref cursor; myResultset myRefCursor; myField1 FIELDTYPE; ... myFieldN FIELDTYPE; begin -- Generate this dynamically subQuery := 'select * from dual'; -- Create main query and open cursor mainQuery := mainQuery || subQuery || ')'; open myResultset for mainQuery; -- Loop through records loop fetch myResultset into myField1, ..., myFieldN; exit when myResultset%NOTFOUND; -- Do something with the record data dbms_output.put_line(myField1 || ' ... ' || myFieldN); end loop; close myResultset; end; /Note that rather than using
fetch intowith individual variables, you can populate an entire record at once, provided you can define the record's field types. That is, if you have created a custom type or your record's type matches a table you already have in your schema. For the latter, you can use:myRecord someTable%ROWTYPE;...in the declaration block, then change the
fetch intostatement to:fetch myResultset into myRecord;...and access record fields using dot notation (e.g.,
myRecord.some_field_name).You say in your comments that the dynamic SQL bit is from the results of some other query. Therefore, in my example code, you could use a regular cursor to loop over these data to create the
subQueryvariable in each instance... Although, incidentally, is there any reason why what you're trying to achieve can't be done with a simplejoin?讨论(0) -
If you need a result set and a ref cursor won't do with a datatype called sys.anydataset. i.e what you seem to want is a pipelined function, but of course with a regular pipelined function you need to define the output structure, which in your case isn't static.
Enter anydataset. this type allows us to dynamically generate types on the fly (at hard parse time only) to allow us to define pipelined functions with varying outputs.
The coding is a bit complex unfortunately.
To start with, we define a type that will do the processing of the passed in SQL statement.
SQL> create type dyn_pipeline as object 2 ( 3 atype anytype, 4 5 static function ODCITableDescribe(rtype out anytype, 6 stmt in varchar2) 7 return number, 8 9 static function ODCITablePrepare(sctx out dyn_pipeline, 10 tf_info in sys.ODCITabfuncinfo, 11 stmt in varchar2) 12 return number, 13 14 static function ODCITableStart(sctx in out dyn_pipeline, 15 stmt in varchar2) 16 return number, 17 18 member function ODCITablefetch(self in out dyn_pipeline, 19 nrows in number, 20 rws out anydataset) 21 return number, 22 23 member function ODCITableClose(self in dyn_pipeline) 24 return number 25 ); 26 /Next up, we create a package spec that will be basically your
querydbfunction call:SQL> create package pkg_pipeline 2 as 3 4 /* 5 * Global Types 6 */ 7 -- Describe array. 8 type dynamic_sql_rec is record(cursor integer, 9 column_cnt pls_integer, 10 description dbms_sql.desc_tab2, 11 execute integer); 12 -- Meta data for the ANYTYPE. 13 type anytype_metadata_rec is record(precision pls_integer, 14 scale pls_integer, 15 length pls_integer, 16 csid pls_integer, 17 csfrm pls_integer, 18 schema varchar2(30), 19 type anytype, 20 name varchar2(30), 21 version varchar2(30), 22 attr_cnt pls_integer, 23 attr_type anytype, 24 attr_name varchar2(128), 25 typecode pls_integer); 26 27 28 /* 29 * Global Variables 30 */ 31 -- SQL descriptor. 32 r_sql dynamic_sql_rec; 33 34 /* 35 * function will run the given SQL 36 */ 37 function querydb(p_stmt in varchar2) 38 return anydataset pipelined using dyn_pipeline; 39 40 end pkg_pipeline; 41 / Package created.the types there will just hold some info about the SQL structure itself (we will be using
DBMS_SQLto describe the input SQL as it has functions to get the number of columns, data types etc out of any given SQL statement.The main type body is where the processing occurs:
SQL> create type body dyn_pipeline 2 as 3 4 /* 5 * DESC step. this will be called at hard parse and will create 6 * a physical type in the DB Schema based on the select columns. 7 */ 8 static function ODCITableDescribe(rtype out anytype, 9 stmt in varchar2) 10 return number 11 is 12 13 /* Variables */ 14 -- Type to hold the dbms_sql info (description) 15 r_sql pkg_pipeline.dynamic_sql_rec; 16 -- Type to create (has all the columns) of the sql query. 17 t_anyt anytype; 18 -- SQL query that will be made up from the 2 passed in queries. 19 v_sql varchar2(32767); 20 21 begin 22 23 /* 24 * Parse the SQL and describe its format and structure. 25 */ 26 v_sql := replace(stmt, ';', null); 27 28 -- open, parse and discover all info about this SQL. 29 r_sql.cursor := dbms_sql.open_cursor; 30 dbms_sql.parse( r_sql.cursor, v_sql, dbms_sql.native ); 31 dbms_sql.describe_columns2( r_sql.cursor, r_sql.column_cnt, r_sql.description ); 32 dbms_sql.close_cursor( r_sql.cursor ); 33 34 -- Start to create the physical type. 35 anytype.BeginCreate( DBMS_TYPES.TYPECODE_OBJECT, t_anyt ); 36 37 -- Loop through each attribute and add to the type. 38 for i in 1 .. r_sql.column_cnt 39 loop 40 41 t_anyt.AddAttr(r_sql.description(i).col_name, 42 case 43 when r_sql.description(i).col_type in (1,96,11,208) 44 then dbms_types.typecode_varchar2 45 when r_sql.description(i).col_type = 2 46 then dbms_types.typecode_number 47 when r_sql.description(i).col_type in (8,112) 48 then dbms_types.typecode_clob 49 when r_sql.description(i).col_type = 12 50 then dbms_types.typecode_date 51 when r_sql.description(i).col_type = 23 52 then dbms_types.typecode_raw 53 when r_sql.description(i).col_type = 180 54 then dbms_types.typecode_timestamp 55 when r_sql.description(i).col_type = 181 56 then dbms_types.typecode_timestamp_tz 57 when r_sql.description(i).col_type = 182 58 then dbms_types.typecode_interval_ym 59 when r_sql.description(i).col_type = 183 60 then dbms_types.typecode_interval_ds 61 when r_sql.description(i).col_type = 231 62 then dbms_types.typecode_timestamp_ltz 63 end, 64 r_sql.description(i).col_precision, 65 r_sql.description(i).col_scale, 66 r_sql.description(i).col_max_len, 67 r_sql.description(i).col_charsetid, 68 r_sql.description(i).col_charsetform ); 69 end loop; 70 71 t_anyt.EndCreate; 72 73 -- set the output type to our built type. 74 ANYTYPE.BeginCreate(dbms_types.TYPECODE_TABLE, rtype); 75 rtype.SetInfo(null, null, null, null, null, t_anyt, 76 dbms_types.TYPECODE_OBJECT, 0); 77 rtype.EndCreate(); 78 79 return ODCIConst.Success; 80 81 end ODCITableDescribe; 82 83 84 /* 85 * PREPARE step. Initialise our type. 86 */ 87 static function ODCITableprepare(sctx out dyn_pipeline, 88 tf_info in sys.ODCITabfuncinfo, 89 stmt in varchar2) 90 return number 91 is 92 93 /* Variables */ 94 -- Meta data. 95 r_meta pkg_pipeline.anytype_metadata_rec; 96 97 begin 98 99 r_meta.typecode := tf_info.rettype.getattreleminfo( 100 1, r_meta.precision, r_meta.scale, r_meta.length, 101 r_meta.csid, r_meta.csfrm, r_meta.type, r_meta.name 102 ); 103 104 sctx := dyn_pipeline(r_meta.type); 105 return odciconst.success; 106 107 end; 108 109 110 /* 111 * START step. this is where we execute the cursor prior to fetching from it. 112 */ 113 static function ODCITablestart(sctx in out dyn_pipeline, 114 stmt in varchar2) 115 return number 116 is 117 118 /* Variables */ 119 r_meta pkg_pipeline.anytype_metadata_rec; 120 v_sql varchar2(32767); 121 begin 122 123 v_sql := replace(stmt, ';', null); 124 pkg_pipeline.r_sql.cursor := dbms_sql.open_cursor; 125 dbms_sql.parse(pkg_pipeline.r_sql.cursor, v_sql, dbms_sql.native); 126 dbms_sql.describe_columns2(pkg_pipeline.r_sql.cursor, 127 pkg_pipeline.r_sql.column_cnt, 128 pkg_pipeline.r_sql.description); 129 130 -- define all the columns found to let Oracle know the datatypes. 131 for i in 1..pkg_pipeline.r_sql.column_cnt 132 loop 133 134 r_meta.typecode := sctx.atype.GetAttrElemInfo( 135 i, r_meta.precision, r_meta.scale, r_meta.length, 136 r_meta.csid, r_meta.csfrm, r_meta.type, r_meta.name 137 ); 138 139 case r_meta.typecode 140 when dbms_types.typecode_varchar2 141 then 142 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, '', 32767); 143 when dbms_types.typecode_number 144 then 145 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as number)); 146 when dbms_types.typecode_date 147 then 148 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as date)); 149 when dbms_types.typecode_raw 150 then 151 dbms_sql.define_column_raw(pkg_pipeline.r_sql.cursor, i, cast(null as raw), r_meta.length); 152 when dbms_types.typecode_timestamp 153 then 154 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as timestamp)); 155 when dbms_types.typecode_timestamp_tz 156 then 157 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as timestamp with time zone)); 158 when dbms_types.typecode_timestamp_ltz 159 then 160 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as timestamp with local time zone)); 161 when dbms_types.typecode_interval_ym 162 then 163 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as interval year to month)); 164 when dbms_types.typecode_interval_ds 165 then 166 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as interval day to second)); 167 when dbms_types.typecode_clob 168 then 169 case pkg_pipeline.r_sql.description(i).col_type 170 when 8 171 then 172 dbms_sql.define_column_long(pkg_pipeline.r_sql.cursor, i); 173 else 174 dbms_sql.define_column(pkg_pipeline.r_sql.cursor, i, cast(null as clob)); 175 end case; 176 end case; 177 end loop; 178 179 -- execute the SQL. 180 pkg_pipeline.r_sql.execute := dbms_sql.execute(pkg_pipeline.r_sql.cursor); 181 182 return odciconst.success; 183 184 end ODCITablestart; 185 186 187 /* 188 * FETCH step. 189 */ 190 member function ODCITablefetch(self in out dyn_pipeline, 191 nrows in number, 192 rws out anydataset) 193 return number 194 is 195 196 /* Variables */ 197 -- Buffers to hold values. 198 v_vc_col varchar2(32767); 199 v_num_col number; 200 v_date_col date; 201 v_raw_col raw(32767); 202 v_raw_error number; 203 v_raw_len integer; 204 v_int_ds_col interval day to second; 205 v_int_ym_col interval year to month; 206 v_ts_col timestamp; 207 v_tstz_col timestamp with time zone; 208 v_tsltz_col timestamp with local time zone; 209 v_clob_col clob; 210 v_clob_offset integer := 0; 211 v_clob_len integer; 212 -- Metadata 213 r_meta pkg_pipeline.anytype_metadata_rec; 214 215 begin 216 217 if dbms_sql.fetch_rows( pkg_pipeline.r_sql.cursor ) > 0 218 then 219 220 -- Describe to get number and types of columns. 221 r_meta.typecode := self.atype.getinfo( 222 r_meta.precision, r_meta.scale, r_meta.length, 223 r_meta.csid, r_meta.csfrm, r_meta.schema, 224 r_meta.name, r_meta.version, r_meta.attr_cnt 225 ); 226 227 anydataset.begincreate(dbms_types.typecode_object, self.atype, rws); 228 rws.addinstance(); 229 rws.piecewise(); 230 231 -- loop through each column extracting value. 232 for i in 1..pkg_pipeline.r_sql.column_cnt 233 loop 234 235 r_meta.typecode := self.atype.getattreleminfo( 236 i, r_meta.precision, r_meta.scale, r_meta.length, 237 r_meta.csid, r_meta.csfrm, r_meta.attr_type, 238 r_meta.attr_name 239 ); 240 241 case r_meta.typecode 242 when dbms_types.typecode_varchar2 243 then 244 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_vc_col); 245 rws.setvarchar2(v_vc_col); 246 when dbms_types.typecode_number 247 then 248 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_num_col); 249 rws.setnumber(v_num_col); 250 when dbms_types.typecode_date 251 then 252 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_date_col); 253 rws.setdate(v_date_col); 254 when dbms_types.typecode_raw 255 then 256 dbms_sql.column_value_raw(pkg_pipeline.r_sql.cursor, i, v_raw_col, 257 v_raw_error, v_raw_len); 258 rws.setraw(v_raw_col); 259 when dbms_types.typecode_interval_ds 260 then 261 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_int_ds_col); 262 rws.setintervalds(v_int_ds_col); 263 when dbms_types.typecode_interval_ym 264 then 265 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_int_ym_col); 266 rws.setintervalym(v_int_ym_col); 267 when dbms_types.typecode_timestamp 268 then 269 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_ts_col); 270 rws.settimestamp(v_ts_col); 271 when dbms_types.typecode_timestamp_tz 272 then 273 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_tstz_col); 274 rws.settimestamptz(v_tstz_col); 275 when dbms_types.typecode_timestamp_ltz 276 then 277 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_tsltz_col); 278 rws.settimestampltz(v_tsltz_col); 279 when dbms_types.typecode_clob 280 then 281 case pkg_pipeline.r_sql.description(i).col_type 282 when 8 283 then 284 loop 285 dbms_sql.column_value_long(pkg_pipeline.r_sql.cursor, i, 32767, v_clob_offset, 286 v_vc_col, v_clob_len); 287 v_clob_col := v_clob_col || v_vc_col; 288 v_clob_offset := v_clob_offset + 32767; 289 exit when v_clob_len < 32767; 290 end loop; 291 else 292 dbms_sql.column_value(pkg_pipeline.r_sql.cursor, i, v_clob_col); 293 end case; 294 rws.setclob(v_clob_col); 295 end case; 296 end loop; 297 298 rws.endcreate(); 299 300 end if; 301 302 return ODCIConst.Success; 303 304 end; 305 306 /* 307 * CLOSE step. close the cursor. 308 */ 309 member function ODCITableClose(self in dyn_pipeline) 310 return number 311 is 312 313 314 begin 315 dbms_sql.close_cursor( pkg_pipeline.r_sql.cursor ); 316 pkg_pipeline.r_sql := null; 317 return odciconst.success; 318 end ODCITableClose; 319 320 end; 321 / Type body created.once this is done, you can query like:
SQL> select * from table(pkg_pipeline.querydb('select * from dual')); D - X SQL> select * from table(pkg_pipeline.querydb('select * from v$mystat where rownum <= 2')); SID STATISTIC# VALUE ---------- ---------- ---------- 230 0 1 230 1 1讨论(0)
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