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This example creates a new table called ThisTable with two text fields. This means that within a given table, for a given MEMO column, some data may be compressed and some data may not be compressed. All other instances of MEMO columns will remain uncompressed. Only instances of MEMO columns that, when compressed, will fit within 4096 bytes or less, will be compressed. MEMO columns can also be defined to store data in a compressed format. If you define a CHARACTER column with this attribute, data will automatically be compressed as it is stored and uncompressed when retrieved from the column. However, Unicode representation of many character sets, those formerly denoted as Single-Byte Character Sets (SBCS), can easily be compressed to a single byte. For existing Microsoft Jet databases that contain predominately character data, this could mean that the database file would nearly double in size when converted to the Microsoft Access database engine format. Unicode characters uniformly require two bytes for each character. The WITH COMPRESSION attribute was added for CHARACTER columns because of the change to the Unicode character representation format. The WITH COMPRESSION attribute can be used only with the CHARACTER and MEMO (also known as TEXT) data types and their synonyms. Temporary tables can be accessed by more than one user. It is automatically deleted when the session is terminated. When a TEMPORARY table is created, it is visible only within the session in which it was created. Attempting to apply this restriction more than once results in a run-time error. However, you can apply the NOT NULL restriction only once to a field. You can use NOT NULL on a single field or within a named CONSTRAINT clause that applies to either a single field or to a multiple-field named CONSTRAINT. You can also use the CREATE INDEX statement to create a primary key or additional indexes on existing tables. If NOT NULL is specified for a field, new records are required to have valid data in that field.Ī CONSTRAINT clause establishes various restrictions on a field, and can be used to establish the primary key. Use the CREATE TABLE statement to define a new table and its fields and field constraints.
#MICROSOFT ACCESS PRIMARY KEY HOW TO#
For more information about how to create this index, see CONSTRAINT clause. For more information about how to create this index, see CONSTRAINT clause.Ī CONSTRAINT clause defining a multiple-field index. The field size in characters (Text and Binary fields only).Ī CONSTRAINT clause defining a single-field index. The name of field or fields to be created in the new table. The CREATE TABLE statement has these parts: SyntaxĬREATE TABLE table ( field1 type ] ]) RE: Primary key thinks upper and lower case are the same.The Microsoft Access database engine does not support the use of CREATE TABLE, or any of the DDL statements, with non-Microsoft Access database engine databases. because we normally apply a standard of uppercase for all key columns and build this into the form's data validation code. I suspect there is a bug in our Ingres apps.
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updates the relevant record(s) in Access using the key(s) to reference the record(s).
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When tables change in Ingres a rule(trigger) is fired and the Delphi app. Why I need this: I'm synchronising an Ingres 6.4 DB with Access using a background application, (C++Builder/Delphi). I've thought about creating another table in Access to hold the 'duplicates' - but then need messy UNIONs in all joins.
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Q2 Do you know of any environment/global variables that may influence the Access default behaviour for a database instance, or hopefully at least at the table-level, if not column-level? Q1 Do you know how I can create a table in Access so that columns are case-sensitive? For example, Access treats "LC1030280T" and "LC1030280t" as the same and therefore I cannot build a key or index on this column. I cannot create a key or non-duplicate index on a column whose values may be differentiated only by case. Problem: Primary key thinks upper and lower case are the same.