ToC path:

mco_uda_lookup

Perform a database lookup.

Prototype

 
    MCO_RET mco_uda_lookup(	/*IN*/ mco_trans_h t,
                  /*IN*/ unsigned short struct_no,
                  /*IN*/ unsigned short index_no,
                  /*IN*/ MCO_OPCODE op, 
                  /*IN*/ const mco_uda_value_t * keys,
                   /*IN*/ unsigned short keys_count, 
                  /*OUT*/ mco_cursor_t * cursor );

Arguments

t	The transaction handle
struct_no	The structure/class number (must be between 0 and `mco_dict_struct_count()` - 1)
index_no	The index number (must be between 0 and `struct_info.index_count` - 1)
op	The opcode (MCO_LT, MCO_LE, MCO_EQ, MCO_GE, MCO_GT) Note that a hash index only allows MCO_EQ
keys	An array of search keys
keys_count	The length of the search keys array. Note that the number of keys, their order and types must correspond to the DDL description for the index
cursor	The cursor handle

Description

Perform a database lookup. The function positions the cursor at the first object that satisfies the search criteria. The object handle can then be received using the mco_uda_from_cursor() API.

Return Codes

MCO_S_OK	Object found
MCO_E_UDA_STRUCT_NOTFOUND	Invalid `struct_no`
MCO_E_UDA_STRUCT_NOT_CLASS	Invalid `struct_no` (not a class)
MCO_E_UDA_INDEX_NOTFOUND	Invalid `index_no`
MCO_E_UDA_WRONG_KEY_NUM	Mismatch between `keys_count` and actual number of keys defined in the index
MCO_E_UDA_WRONG_KEY_TYPE	Key type mismatch
MCO_E_UDA_WRONG_OPCODE	Invalid opcode (must be MCO_LT, MCO_LE, MCO_EQ, MCO_GE, or MCO_GT; and only MCO_EQ for a hash index)

Example

 
    Application snippet:
        
     
    int main(int argc, char* argv[])
    {
        MCO_RET rc;
        mco_db_h db;
        mco_trans_h t;
        mco_cursor_t csr;
        mco_uda_value_t keys[1];
        unsigned short struct_no = 1;
        unsigned short index_no = 2;
        mco_uda_object_handle_t uda_obj;
        ...
 
        rc = mco_trans_start(db, MCO_READ_WRITE, MCO_TRANS_FOREGROUND, &t);
        if ( MCO_S_OK == rc)
        {
            ...
            keys[0].type = MCO_DD_UINT4;
            keys[0].u4   = 120;
            /* Lookup the first object with id >= 120. */
            rc = mco_uda_lookup(t, Record_struct_no, index_no, MCO_GE, 
                        keys, 1, &csr); 
            if ( MCO_S_OK == rc) 
            {
                mco_uda_from_cursor(t, &csr, &uda_obj); /* get the handle */
                ...
            }
        }
        ...
    }

Files

Header file:

mcouda.h

Source file:

mcouda.c

Library:

libmcouda.a