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Query Rows

Select Rows

SELECT id,name,age,class,score from student WHERE id = 2;

xdb_res_t *pRes = xdb_exec (pConn, "SELECT id,name,age,class,score from student WHERE id = 2");

xdb_res_t *pRes = xdb_pexec (pConn, "SELECT id,name,age,class,score from student WHERE id = %d", id);

// check pRes->errcode = 0

Get Row Count

pRes->row_count;

Get Column information

for (int i = 0; i < pRes->col_count; ++i) {
    xdb_col_t *pCol = xdb_column_meta (pRes, i);
    printf ("type %d name %s\n", pCol->type, pCol->name);
}

Fetch One Row

xdb_row_t *pRow = xdb_fetch_row (pRes);

Get Column Values

  • Access by column data type
printf ("char value %d\n",      *(char*)pRow[0]);
printf ("short value %d\n",     *(short*)pRow[1]);
printf ("int value %d\n",       *(int*)pRow[2]);
printf ("bigint value %"PRIi64"\n", *(int64_t*)pRow[3]);
printf ("float value %f\n",     *(float*)pRow[4]);
printf ("double value %d\n",    *(double*)pRow[5]);
printf ("string value %s\n",    *(char*)pRow[6]);
printf ("string len   %d\n",    *(uint16_t*)(pRow[6]-2));
  • Access by API
printf ("char value %d\n",      xdb_column_int(pRes->col_meta, pRow, 0));
printf ("short value %d\n",     xdb_column_int(pRes->col_meta, pRow, 1));
printf ("int value %d\n",       xdb_column_int(pRes->col_meta, pRow, 2));
printf ("bigint value %"PRIi64"\n", xdb_column_int64(pRes->col_meta, pRow, 3));
printf ("float value %f\n",     xdb_column_float(pRes->col_meta, pRow, 4));
printf ("double value %d\n",    xdb_column_double(pRes->col_meta, pRow, 5));
printf ("string value %s\n",    xdb_column_str(pRes->col_meta, pRow, 6));
int len;
printf ("string value %s, len %d\n", xdb_column_str2(pRes->col_meta, pRow, 6, &len), len);

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