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8 mar 2021 · select jobs, coalesce(salary, 0) as salary. from your_table. Or DECODE. select jobs, decode(salary, null, 0, salary) as salary. from your_table. Or CASE. select jobs, case when salary is null then 0 else salary end as salary. from your_table. For example (based on scott's EMP table):
19 kwi 2018 · Oracle usually treats an empty string as NULL: COALESCE(LENGTH(p.firstName), 0) + COALESCE(LENGTH(p.lastName),0)
4 sty 2011 · NULL means absence of value (i.e. there is no value), while empty string means there is a string value of zero length. For example, say you have a table to store a person' data and it contains a Gender column. You can save the values as 'Male' or 'Female'.
Use a null when the actual value is not known or when a value would not be meaningful. Oracle Database treats a character value with a length of zero as null. However, do not use null to represent a numeric value of zero, because they are not equivalent.
7 gru 2022 · TO_NUMBER converts ONLY the value , If NULL is specified for string-expression, TO_NUMBER returns null . CAST can convert both the value AND the metadata. With TO_NUMBER , NULL is specified for a column, but the type is not specified so the table can't be created.
DROP TABLE null_test_tab; CREATE TABLE null_test_tab ( id NUMBER, col1 VARCHAR2(10), col2 VARCHAR2(10), col3 VARCHAR2(10), col4 VARCHAR2(10) ); INSERT INTO null_test_tab values (1, 'ONE', 'TWO', 'THREE', 'FOUR'); INSERT INTO null_test_tab values (2, NULL, 'TWO', 'THREE', 'FOUR'); INSERT INTO null_test_tab values (3, NULL, NULL, 'THREE', 'FOUR ...
To concatenate an expression that might be null, use the NVL function to explicitly convert the expression to a zero-length string. Example This example creates a table with both CHAR and VARCHAR2 columns, inserts values both with and without trailing blanks, and then selects these values, concatenating them.
