Answer to Question #25186 in Databases | SQL | Oracle | MS Access for Joe

Question #25186
I am trying to update a field in MySql: the basic premis is: FIeld X = Field Y + 30 (both X and Y are numeric) Both fields are in the same table. I tried update <tablename> set X = (Y+30) where condition = Z I then tried update <tablename> set X = sum (Y+30) where condition = Z both failed. Can you help?
Expert's answer
There are some rules for updating field in MySQL table:
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1. At the update moment table must exists in database
2. if X-field has PRIMARYor UNIQUE& key property - You must exclude inserting of duplicate values into that field, or have to use syntax: "UPDATE [IGNORE] tbl_name...". So duplicate values will be excluded and update will execute without an error messages.
3. Table names used with schema name, so Your sql-command must has format as:

update schema_name.tablename set X = (Y+30) where condition = Z
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4. Check - You have enough DB rights to update tables.

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