Question

list of let statement and their description​

Answer 1

Answer:

Explanation:

With a LET statement, you can use one or more variable names with an equal (=) sign and a valid expression or function name. Each example in the following figure is a valid LET statement.

Figure 1. Valid LET statements.

LET a = 5;

LET b = 6; LET c = 10;

LET a,b = 10,c+d;

LET a,b = (SELECT cola,colb  

    FROM tab1 WHERE cola=10);

LET d = func1(x,y);Copy

IBM® Informix® allows you to assign a value to an opaque-type variable, a row-type variable, or a field of a row type. You can also return the value of an external function or another SPL function to an SPL variable.

Suppose you define the named row types zip_t and address_t, as Figure 1 shows. Anytime you define a row-type variable, you must initialize the variable before you can use it. The following figure shows how you might define and initialize a row-type variable. You can use any row-type value to initialize the variable.

Figure 2. Define and initialize a row-type variable.

DEFINE a address_t;

LET a = ROW ('A Street', 'Nowhere', 'AA',  

        ROW(NULL, NULL))::address_tCopy

After you define and initialize the row-type variable, you can write the LET statements that the following figure shows.

Figure 3. Write the LET statements.

LET a.zip.z_code = 32601;

LET a.zip.z_suffix = 4555;

  -- Assign values to the fields of address_tCopy

If you define an opaque-type center that defines a point as the center of a circle, and a function circum() that calculates the circumference of a circle, based on a point and the radius, you can write variable declarations for each. In the following figure, c is an opaque type variable and d holds the value that the external function circum() returns.

Figure 4. Writing variable declarations.

DEFINE c point;

DEFINE r REAL;

DEFINE d REAL;

LET c = '(29.9,1.0)' ;

  -- Assign a value to an opaque type variable

LET d = circum( c, r );

  -- Assign a value returned from circum()