Luca Porfiri wrote :
> =
> Hy all!
> =
> Could someone help me to understand the meaning?
> =
> This is the structure of sql string:
> =
> SELECT *
> =
> FROM table_1, table_2
> =
> WHERE
> =
> field_1.table_2 =3D field_2.table_1
> AND
> field_2.table_2 =3D "y"
> AND
> field_1.table_1 =3D "x"
> AND
> field_3.table_1 =3D "z"
> =
> it will search and find as the last query didn't exist. alias it consid=
ers
> anly the first statement after searching in table_2
> =
> What's the rule?
First, you must write :
tableName.fieldName
and not
fieldName.tableName
Next, the order is :
1. SELECT
2. fieldName list
3. FROM
4. tableName list
Followed optionnaly by:
5. WHERE
6. LinkConditions (if many tables)
7. SearchConditions
8. ORDER BY
9. fieldName [DESC]
The LinkConditions may be in any order I think.
The SearchConditions must be grouped by table (within parenthesis if
many conditions for a table) :
SELECT * =
FROM table_1, table_2
WHERE table_2.field_1 =3D table_1.field_2
AND
table_2.field_2 =3D "y"
AND
(table_1.field_1 =3D "x" AND table_2.field_3 =3D "z")
Best regards.
Fran=E7ois Van Lerberghe
Thier Monty, 15A
B-4570 Marchin
Belgique
©2002 Francois Van Lerberghe |
