As indicated above, host variables are used to store the result of an SQL query. The resulting value is put INTO the variable.
SELECT database-field(s) INTO :host-variable
database-field(s) is one or more variables defined in Working-Storage.
host-variable is the name of a COBOL variable.
The select1.sqb program contains the following code:
EXEC SQL SELECT C_FIRST_NAME, C_LAST_NAME, C_BIRTHDAY, C_INFO INTO :C-FIRST-NAME, :C-LAST-NAME, :C-BIRTHDAY, :C-INFO FROM CUSTOMER ... END-EXEC.
This series of statements instructs the program to place the values for these fields INTO the corresponding COBOL variables, which are C-FIRST-NAME, C-LAST-NAME, etc., so that COBOL statements can refer to them. The semicolon in the code indicates that these are COBOL (host) variables.